UIApplication

Inherits From

NSObject
UIResponder
UIApplication

NSObject
UIResponder
UIApplication

Conforms To

Import Statement

Objective-C

@import UIKit;

Swift

import UIKit

Availability

Available in iOS 2.0 and later

The UIApplication class provides a centralized point of control and coordination for apps running in iOS. Every app has exactly one instance of UIApplication (or, very rarely, a subclass of UIApplication). When an app is launched, the system calls the UIApplicationMain function; among its other tasks, this function creates a singleton UIApplication object. Thereafter you access the object by calling the sharedApplication class method.

A major role of your app’s application object is to handle the initial routing of incoming user events. It dispatches action messages forwarded to it by control objects (instances of the UIControl class) to appropriate target objects. The application object maintains a list of open windows (UIWindow objects) and through those can retrieve any of the app’s UIView objects.

The UIApplication class defines a delegate that conforms to the UIApplicationDelegate protocol and must implement some of the protocol’s methods. The application object informs the delegate of significant runtime events—for example, app launch, low-memory warnings, and app termination—giving it an opportunity to respond appropriately.

Apps can cooperatively handle a resource, such as an email or an image file, through the openURL: method. For example, an app that calls this method with an email URL causes the Mail app to launch and display the message.

The APIs in this class allow you to manage device-specific behavior. Use your UIApplication object to do the following:

Temporarily suspend incoming touch events (beginIgnoringInteractionEvents)
Register for remote notifications (unregisterForRemoteNotifications)
Trigger the undo-redo UI (applicationSupportsShakeToEdit)
Determine whether there is an installed app registered to handle a URL scheme (canOpenURL:)
Extend the execution of the app so that it can finish a task in the background (beginBackgroundTaskWithExpirationHandler:, beginBackgroundTaskWithName:expirationHandler:)
Schedule and cancel local notifications (scheduleLocalNotification:, cancelLocalNotification:)
Coordinate the reception of remote-control events (beginReceivingRemoteControlEvents, endReceivingRemoteControlEvents)
Perform app-level state restoration tasks (methods in the Managing the State Restoration Behavior task group)

Subclassing Notes

Most apps do not need to subclass UIApplication. Instead, use an app delegate to manage interactions between the system and the app.

If your app must handle incoming events before the system does—a very rare situation—you can implement a custom event or action dispatching mechanism. To do this, subclass UIApplication and override the sendEvent: and/or the sendAction:to:from:forEvent: methods. For every event you intercept, dispatch it back to the system by calling [super sendEvent:event] after you handle the event. Intercepting events is only rarely required and you should avoid it if possible.

Getting the App Instance

sharedApplication() + sharedApplication

Returns the singleton app instance.

Declaration

Swift

class func sharedApplication() -> UIApplication

Objective-C

+ (UIApplication *)sharedApplication

Return Value

The app instance is created in the UIApplicationMain function.

Availability

Available in iOS 2.0 and later.

Not available in app extensions.

Getting the App Delegate

delegate delegate Property

The delegate of the app object.

Declaration

Swift

unowned(unsafe) var delegate: UIApplicationDelegate?

Objective-C

@property(nonatomic, assign) id< UIApplicationDelegate > delegate

Discussion

Every app must have an app delegate object to respond to app-related messages. For example, the app notifies its delegate when the app finishes launching and when its foreground or background execution status changes. Similarly, app-related messages coming from the system are often routed to the app delegate for handling. Xcode provides an initial app delegate for every app and you should not need to change this delegate later.

The delegate must adopt the UIApplicationDelegate formal protocol.

Availability

Available in iOS 2.0 and later.

Getting App Windows

keyWindow keyWindow Property

The app's key window. (read-only)

Declaration

Swift

var keyWindow: UIWindow? { get }

Objective-C

@property(nonatomic, readonly) UIWindow *keyWindow

Discussion

This property holds the UIWindow object in the windows array that is most recently sent the makeKeyAndVisible message.

Availability

Available in iOS 2.0 and later.

See Also

windows
windows windows Property

The app's visible and hidden windows. (read-only)

Declaration

Swift

var windows: [UIWindow] { get }

Objective-C

@property(nonatomic, readonly) NSArray <__kindof UIWindow *> *windows

Discussion

This property contains the UIWindow objects currently associated with the app. This list does not include windows created and managed by the system, such as the window used to display the status bar.

The windows in the array are ordered from back to front by window level; thus, the last window in the array is on top of all other app windows.

Availability

Available in iOS 2.0 and later.

See Also

keyWindow

Controlling and Handling Events

sendEvent(_:) - sendEvent:

Dispatches an event to the appropriate responder objects in the app.

Declaration

Swift

func sendEvent(_ event: UIEvent)

Objective-C

- (void)sendEvent:(UIEvent *)event

Parameters

event

A UIEvent object encapsulating the information about an event, including the touches involved.

Discussion

If you require it, you can intercept incoming events by subclassing UIApplication and overriding this method. For every event you intercept, you must dispatch it by calling [super sendEvent:event] after handling the event in your implementation.

Availability

Available in iOS 2.0 and later.

See Also

– sendAction:to:from:forEvent:


    
      
           sendAction(_:to:from:forEvent:)
      
      
           - sendAction:to:from:forEvent:

Sends an action message identified by selector to a specified target.

Declaration

Swift

func sendAction(_ action: Selector, to target: AnyObject?, from sender: AnyObject?, forEvent event: UIEvent?) -> Bool

Objective-C

- (BOOL)sendAction:(SEL)action to:(id)target from:(id)sender forEvent:(UIEvent *)event

Parameters

`action`	A selector identifying an action method. See the discussion for information on the permitted selector forms.
`target`	The object to receive the action message. If `target` is `nil`, the app sends the message to the first responder, from whence it progresses up the responder chain until it is handled.
`sender`	The object that is sending the action message. The default sender is the `UIControl` object that invokes this method.
`event`	A `UIEvent` object that encapsulates information about the event originating the action message.

Return Value

YEStrue if a responder object handled the action message, NOfalse if no object in the responder chain handled the message.

Discussion

Normally, this method is invoked by a UIControl object that the user has touched. The default implementation dispatches the action method to the given target object or, if no target is specified, to the first responder. Subclasses may override this method to perform special dispatching of action messages.

By default, this method pushes two parameters when calling the target. These last two parameters are optional for the receiver because it is up to the caller (usually a UIControl object) to remove any parameters it added. This design enables the action selector to be one of the following:

- (void)action
- (void)action:(id)sender
- (void)action:(id)sender forEvent:(UIEvent *)event

Availability

Available in iOS 2.0 and later.

Opening a URL Resource


    
      
           openURL(_:)
      
      
           - openURL:

Attempts to open the resource at the specified URL.

Declaration

Swift

func openURL(_ url: NSURL) -> Bool

Objective-C

- (BOOL)openURL:(NSURL *)url

Parameters

url

A URL (Universal Resource Locator). UIKit supports many common schemes, including the http, https, tel, facetime, and mailto schemes. You can also employ custom URL schemes associated with apps installed on the device.

Return Value

YEStrue if the resource located by the URL was successfully opened; otherwise NOfalse.

Discussion

The URL you pass to this method can identify a resource in the app that calls the method, or a resource to be handled by another app. If the resource is to be handled another app, invoking this method might cause the calling app to quit so the other can launch.

To check if there is an installed app that can handle a scheme, call the canOpenURL: method before calling this one. Be sure to read the description of that method for an important note about registering the schemes you want to employ.

Availability

Available in iOS 2.0 and later.

Not available in app extensions.

Declaration

Swift

func canOpenURL(_ url: NSURL) -> Bool

Objective-C

- (BOOL)canOpenURL:(NSURL *)url

Parameters

url

A URL (Universal Resource Locator). At runtime, the system tests the URL’s scheme to determine if there is an installed app that is registered to handle the scheme. More than one app can be registered to handle a scheme.

The URL you pass to this method can have a common scheme or a custom scheme.

Return Value

NOfalse if there is no app installed on the device that is registered to handle the URL’s scheme, or if you have not declared the URL’s scheme in your Info.plist file; otherwise, YEStrue.

Read the Discussion section for more information on conditions that affect the return value.

Discussion

If this method returns YEStrue for a given URL, iOS guarantees that that if the openURL: method is subsequently called using the same URL, an app registered to handle the URL’s scheme will launch to handle it. This method’s return value does not indicate whether or not the full URL is valid or if the specified resource exists.

If your app is linked against an earlier version of iOS but is running in iOS 9.0 or later, you can call this method on 50 distinct URL schemes. After hitting this limit, subsequent calls to this method return NOfalse. If a user reinstalls or upgrades the app, iOS resets the limit.

Unlike this method, the openURL: method is not constrained by the LSApplicationQueriesSchemes requirement: If an app that handles a scheme is installed on the device, the openURL: method works, whether or not you have declared the scheme.

Availability

Available in iOS 3.0 and later.

Configuring the User Notification Settings


    
      
           registerUserNotificationSettings(_:)
      
      
           - registerUserNotificationSettings:

Registers your preferred options for notifying the user.

Declaration

Swift

func registerUserNotificationSettings(_ notificationSettings: UIUserNotificationSettings)

Objective-C

- (void)registerUserNotificationSettings:(UIUserNotificationSettings *)notificationSettings

Parameters


  notificationSettings

The types of notifications that your app wants to use. You also use this object to specify custom actions that can be initiated by the user from an alert displayed in response to a local or remote notification.

Discussion

If your app displays alerts, play sounds, or badges its icon, you must call this method during your launch cycle to request permission to alert the user in these ways. (You must also make this request if you want to set the applicationIconBadgeNumber property directly.) Typically, you make this request if your app uses local or remote notifications to alert the user to new information involving your app. The first time your app launches and calls this method, the system asks the user whether your app should be allowed to deliver notifications and stores the response. Thereafter, the system uses the stored response to determine the actual types of notifications you may use.

After calling this method, the app calls the application:didRegisterUserNotificationSettings: method of its app delegate to report the results. You can use that method to determine if your request was granted or denied by the user.

It is recommended that you call this method before you schedule any local notifications or register with the push notification service. Calling this method with a new user settings object replaces the previous settings request. Apps that support custom actions must include all of their supported actions in the notificationSettings object.

Availability

Available in iOS 8.0 and later.

Registering for Remote Notifications

registerForRemoteNotifications() - registerForRemoteNotifications

Register to receive remote notifications via Apple Push Notification service.

Declaration

Swift

func registerForRemoteNotifications()

Objective-C

- (void)registerForRemoteNotifications

Discussion

Call this method to initiate the registration process with Apple Push Notification service. If registration succeeds, the app calls your app delegate object’s application:didRegisterForRemoteNotificationsWithDeviceToken: method and passes it a device token. You should pass this token along to the server you use to generate remote notifications for the device. If registration fails, the app calls its app delegate’s application:didFailToRegisterForRemoteNotificationsWithError: method instead.

If you want your app’s remote notifications to display alerts, play sounds, or perform other user-facing actions, you must call the registerUserNotificationSettings: method to request the types of notifications you want to use. If you do not call that method, the system delivers all remote notifications to your app silently. Because the registration process takes into account the user’s preferred notification settings, requesting access to user-facing notification types also does not guarantee that they will be granted. To find out what notification settings are available, use the currentUserNotificationSettings method.

Availability

Available in iOS 8.0 and later.

See Also

– registerUserNotificationSettings:
unregisterForRemoteNotifications() - unregisterForRemoteNotifications

Unregister for all remote notifications received via Apple Push Notification service.

Declaration

Swift

func unregisterForRemoteNotifications()

Objective-C

- (void)unregisterForRemoteNotifications

Discussion

You should call this method in rare circumstances only, such as when a new version of the app removes support for all types of remote notifications. Users can temporarily prevent apps from receiving remote notifications through the Notifications section of the Settings app. Apps unregistered through this method can always re-register.

Availability

Available in iOS 3.0 and later.

See Also

– registerForRemoteNotifications
isRegisteredForRemoteNotifications() - isRegisteredForRemoteNotifications

Returns a Boolean indicating whether the app is currently registered for remote notifications.

Declaration

Swift

func isRegisteredForRemoteNotifications() -> Bool

Objective-C

- (BOOL)isRegisteredForRemoteNotifications

Return Value

YEStrue if the app is registered for remote notifications and received its device token or NOfalse if registration has not occurred, has failed, or has been denied by the user.

Discussion

This method reflects only the successful completion of the remote registration process that begins when you call the registerForRemoteNotifications method. This method does not reflect whether remote notifications are actually available due to connectivity issues. The value returned by this method takes into account the user’s preferences for receiving remote notifications.

Availability

Available in iOS 8.0 and later.

Registering for Local Notifications


    
      
           scheduleLocalNotification(_:)
      
      
           - scheduleLocalNotification:

Schedules a local notification for delivery at its encapsulated date and time.

Declaration

Swift

func scheduleLocalNotification(_ notification: UILocalNotification)

Objective-C

- (void)scheduleLocalNotification:(UILocalNotification *)notification

Parameters


  notification

The local notification object that you want to schedule. This object contains information about when to deliver the notification and what to do when that date occurs. The system keeps a copy of this object so you may release the object once it is scheduled.

Discussion

Prior to scheduling any local notifications, you must call the registerUserNotificationSettings: method to let the system know what types of alerts, if any, you plan to display to the user.

Availability

Available in iOS 4.0 and later.

Declaration

Swift

func presentLocalNotificationNow(_ notification: UILocalNotification)

Objective-C

- (void)presentLocalNotificationNow:(UILocalNotification *)notification

Parameters


  notification

A local notification that the operating system presents for the app immediately, regardless of the value of the notification’s fireDate property. Apps running in the background state can immediately present local notifications when there are incoming chats, messages, or updates. Because the operating system copies notification, you may release it once you have scheduled it.

Discussion

Prior to scheduling any local notifications, you must call the registerUserNotificationSettings: method to let the system know what types of alerts, if any, you plan to display to the user.

Availability

Available in iOS 4.0 and later.

Managing Background Execution

applicationState applicationState Property

The runtime state of the app. (read-only)

Declaration

Swift

var applicationState: UIApplicationState { get }

Objective-C

@property(nonatomic, readonly) UIApplicationState applicationState

Discussion

An app may be active, inactive, or running in the background. You can use the value in this property to determine which of these states the app is currently in.

Availability

Available in iOS 4.0 and later.
backgroundTimeRemaining backgroundTimeRemaining Property

The amount of time the app has to run in the background. (read-only)

Declaration

Swift

var backgroundTimeRemaining: NSTimeInterval { get }

Objective-C

@property(nonatomic, readonly) NSTimeInterval backgroundTimeRemaining

Discussion

This property contains the amount of time the app has to run in the background before it may be forcibly killed by the system. While the app is running in the foreground, the value in this property remains suitably large. If the app starts one or more long-running tasks using the beginBackgroundTaskWithExpirationHandler: method and then transitions to the background, the value of this property is adjusted to reflect the amount of time the app has left to run.

Availability

Available in iOS 4.0 and later.
backgroundRefreshStatus backgroundRefreshStatus Property

The ability of the app to be launched into the background so that it can perform background behaviors. (read-only)

Declaration

Swift

var backgroundRefreshStatus: UIBackgroundRefreshStatus { get }

Objective-C

@property(nonatomic, readonly) UIBackgroundRefreshStatus backgroundRefreshStatus

Discussion

This property reflects whether the app can be launched into the background to handle background behaviors, such as processing background location updates and performing background fetches. If your app relies on being launched into the background to perform tasks, you can use the value of this property to determine if doing so is possible and to warn the user if it is not. Do not warn the user if the value of this property is set to UIBackgroundRefreshStatusRestricted; a restricted user does not have the ability to enable multitasking for the app.

Availability

Available in iOS 7.0 and later.


    
      
           setMinimumBackgroundFetchInterval(_:)
      
      
           - setMinimumBackgroundFetchInterval:

Specifies the minimum amount of time that must elapse between background fetch operations.

Declaration

Swift

func setMinimumBackgroundFetchInterval(_ minimumBackgroundFetchInterval: NSTimeInterval)

Objective-C

- (void)setMinimumBackgroundFetchInterval:(NSTimeInterval)minimumBackgroundFetchInterval

Parameters


  minimumBackgroundFetchInterval

The minimum number of seconds that must elapse before another background fetch can be initiated. This value is advisory only and does not indicate the exact amount of time expected between fetch operations.

Discussion

This property has no effect for apps that do not have the UIBackgroundModes key with the fetch value in its Info.plist file.

The default fetch interval for apps is UIApplicationBackgroundFetchIntervalNever. Therefore, you must call this method and set a fetch interval before your app is given background execution time.

Availability

Available in iOS 7.0 and later.


    
      
           beginBackgroundTaskWithName(_:expirationHandler:)
      
      
           - beginBackgroundTaskWithName:expirationHandler:

Marks the beginning of a new long-running background task with the specified name.

Declaration

Swift

func beginBackgroundTaskWithName(_ taskName: String?, expirationHandler handler: (() -> Void)?) -> UIBackgroundTaskIdentifier

Objective-C

- (UIBackgroundTaskIdentifier)beginBackgroundTaskWithName:(NSString *)taskName expirationHandler:(void (^)(void))handler

Parameters

`taskName`	The name to display in the debugger when viewing the background task. If you specify `nil` for this parameter, this method generates a name based on the name of the calling function or method.
`handler`	A handler to be called shortly before the app’s remaining background time reaches 0. You should use this handler to clean up and mark the end of the background task. Failure to end the task explicitly will result in the termination of the app. The handler is called synchronously on the main thread, blocking the app’s suspension momentarily while the app is notified.

Return Value

A unique identifier for the new background task. You must pass this value to the endBackgroundTask: method to mark the end of this task. This method returns UIBackgroundTaskInvalid if running in the background is not possible.

Discussion

The behavior of this method is identical to the behavior of the beginBackgroundTaskWithExpirationHandler: method except for the addition of an explicit name for the task.

Availability

Available in iOS 7.0 and later.


    
      
           beginBackgroundTaskWithExpirationHandler(_:)
      
      
           - beginBackgroundTaskWithExpirationHandler:

Marks the beginning of a new long-running background task.

Declaration

Swift

func beginBackgroundTaskWithExpirationHandler(_ handler: (() -> Void)?) -> UIBackgroundTaskIdentifier

Objective-C

- (UIBackgroundTaskIdentifier)beginBackgroundTaskWithExpirationHandler:(void (^)(void))handler

Parameters


  handler

A handler to be called shortly before the app’s remaining background time reaches 0. You should use this handler to clean up and mark the end of the background task. Failure to end the task explicitly will result in the termination of the app. The handler is called synchronously on the main thread, blocking the app’s suspension momentarily while the app is notified.

Return Value

Discussion

This method lets your app continue to run for a period of time after it transitions to the background. You should call this method at times where leaving a task unfinished might be detrimental to your app’s user experience. For example, your app could call this method to ensure that had enough time to transfer an important file to a remote server or at least attempt to make the transfer and note any errors. You should not use this method simply to keep your app running after it moves to the background.

Each call to this method must be balanced by a matching call to the endBackgroundTask: method. Apps running background tasks have a finite amount of time in which to run them. (You can find out how much time is available using the backgroundTimeRemaining property.) If you do not call endBackgroundTask: for each task before time expires, the system kills the app. If you provide a block object in the handler parameter, the system calls your handler before time expires to give you a chance to end the task.

You can call this method at any point in your app’s execution. You may also call this method multiple times to mark the beginning of several background tasks that run in parallel. However, each task must be ended separately. You identify a given task using the value returned by this method.

To assist with debugging, this method generates a name for the task that is based on the name of the calling method or function. If you want to specify a custom name, use the beginBackgroundTaskWithName:expirationHandler: method instead.

This method can be safely called on a non-main thread.

Availability

Available in iOS 4.0 and later.

Managing the App Idle Timer

idleTimerDisabled idleTimerDisabled Property

A Boolean value that controls whether the idle timer is disabled for the app.

Declaration

Swift

var idleTimerDisabled: Bool

Objective-C

@property(nonatomic, getter=isIdleTimerDisabled) BOOL idleTimerDisabled

Discussion

The default value of this property is NOfalse. When most apps have no touches as user input for a short period, the system puts the device into a "sleep” state where the screen dims. This is done for the purposes of conserving power. However, apps that don't have user input except for the accelerometer—games, for instance—can, by setting this property to YEStrue, disable the “idle timer” to avert system sleep.

Important

You should set this property only if necessary and should be sure to reset it to NOfalse when the need no longer exists. Most apps should let the system turn off the screen when the idle timer elapses. This includes audio apps. With appropriate use of Audio Session Services, playback and recording proceed uninterrupted when the screen turns off. The only apps that should disable the idle timer are mapping apps, games, or programs where the app needs to continue displaying content when user interaction is minimal.

Availability

Available in iOS 2.0 and later.

Managing the State Restoration Behavior

extendStateRestoration() - extendStateRestoration

Tells the app that your code is restoring state asynchronously.

Declaration

Swift

func extendStateRestoration()

Objective-C

- (void)extendStateRestoration

Discussion

UIKit restores your app’s state synchronously on the main thread. If you choose to perform additional state restoration on a secondary thread, call this method to inform UIKit of that fact. You must balance each call to this method with a matching call to the completeStateRestoration method.

Calling this method is a safety precaution in the event that your app crashes at launch time due to problems restoring its state. If you call this method but do not call the matching completeStateRestoration method before a crash occurs, the system throws away any saved state information. Doing so prevents your app from crashing during subsequent launches because of issues caused by trying to restore your app’s state.

Availability

Available in iOS 6.0 and later.

See Also

– completeStateRestoration
completeStateRestoration() - completeStateRestoration

Tells the app that your code has finished any asynchronous state restoration.

Declaration

Swift

func completeStateRestoration()

Objective-C

- (void)completeStateRestoration

Discussion

UIKit restores your app’s state synchronously on the main thread. If you choose to perform additional state restoration on a secondary thread, call the extendStateRestoration method to inform UIKit of that fact. Call this method after you finish with your background work to let the system know that state restoration is complete.

Availability

Available in iOS 6.0 and later.

See Also

– extendStateRestoration
ignoreSnapshotOnNextApplicationLaunch() - ignoreSnapshotOnNextApplicationLaunch

Prevents the app from using the recent snapshot image during the next launch cycle.

Declaration

Swift

func ignoreSnapshotOnNextApplicationLaunch()

Objective-C

- (void)ignoreSnapshotOnNextApplicationLaunch

Discussion

As part of the state preservation process, UIKit captures your app’s user interface and stores it in an image file. When your app is relaunched, the system displays this snapshot image in place of your app’s default launch image to preserve the notion that your app was still running. If you feel that the snapshot cannot correctly reflect your app’s user interface when your app is relaunched, call this method to let UIKit know that it should use your app’s default launch image instead of the snapshot.

You must call this method from within the code you use to preserve your app’s state.

Availability

Available in iOS 7.0 and later.


    
      
           registerObjectForStateRestoration(_:restorationIdentifier:)
      
      
           + registerObjectForStateRestoration:restorationIdentifier:

Registers a custom object for use with the state restoration system.

Declaration

Swift

class func registerObjectForStateRestoration(_ object: UIStateRestoring, restorationIdentifier restorationIdentifier: String)

Objective-C

+ (void)registerObjectForStateRestoration:(id<UIStateRestoring>)object restorationIdentifier:(NSString *)restorationIdentifier

Parameters

`object`	The object to be registered with the restoration archive. The object must adopt the `UIStateRestoring` protocol. This parameter must not be `nil`.
`restorationIdentifier`	The restoration identifier for the object. UIKit uses this parameter to distinguish the object from other objects in the archive. This parameter must not be `nil`.

Discussion

You use this method to register objects that you want to save as part of the overall state restoration process. Registering the object makes it available for inclusion in the restoration archive but does not automatically include it. To include the object, refer to it from one of your other interface objects. For example, you might write out a reference to the object from the encodeRestorableStateWithCoder: method of one of your view controllers.

Availability

Available in iOS 7.0 and later.

Managing Home Screen Quick Actions for 3D Touch

shortcutItems shortcutItems Property

The Home screen dynamic quick actions for your app; available on devices that support 3D Touch.

Declaration

Swift

var shortcutItems: [UIApplicationShortcutItem]?

Objective-C

@property(nonatomic, copy) NSArray <UIApplicationShortcutItem *> *shortcutItems

Discussion

Set this property to register an array of dynamic quick actions to display on the Home screen when a user presses your app icon. Read this property to retrieve the currently registered Home screen dynamic quick actions.

The items in the shortcutItems array are instances of the UIApplicationShortcutItem class, and are therefore immutable.

Terminology: Dynamic vs. Static Quick Actions

The items in an application object’s shortcutItems array, although immutable, are considered dynamic to distinguish them from the static quick actions you can specify at build time in the UIApplicationShortcutItems array in your Xcode project’s Info.plist file. You create dynamic quick actions, and register them with your application object, at runtime.

The system populates the displayed set of Home screen quick actions, starting at the top, first with your static quick actions. Only if there are additional positions available does it also show your dynamic quick actions, up to the system-defined limit.

The onscreen ordering of your Home screen quick actions reflects the ordering in your UIApplicationShortcutItems array (if that array contains items) and the ordering of the items in the shortcutItems array (if any are displayed).

Note

When you read the value of this property, you obtain an array that contains, exclusively, your dynamic Home screen quick actions. Any static quick actions you’ve defined are not represented in this property’s value.

Availability

Available in iOS 9.0 and later.

Determining the Availability of Protected Content

protectedDataAvailable protectedDataAvailable Property

A Boolean value indicating whether content protection is active. (read-only)

Declaration

Swift

var protectedDataAvailable: Bool { get }

Objective-C

@property(nonatomic, readonly, getter=isProtectedDataAvailable) BOOL protectedDataAvailable

Discussion

The value of this property is NOfalse if data protection is enabled and the device is currently locked. The value of this property is set to YEStrue if the device is unlocked or if content protection is not enabled.

When the value of this property is NOfalse, files that were assigned the NSFileProtectionComplete or NSFileProtectionCompleteUnlessOpen protection key cannot be read or written by your app. The user must unlock the device before your app can access them.

Availability

Available in iOS 4.0 and later.

Registering for Remote Control Events

beginReceivingRemoteControlEvents() - beginReceivingRemoteControlEvents

Tells the app to begin receiving remote-control events.

Declaration

Swift

func beginReceivingRemoteControlEvents()

Objective-C

- (void)beginReceivingRemoteControlEvents

Discussion

In iOS 7.1 and later, use the shared MPRemoteCommandCenter object to register for remote control events. You do not need to call this method when using the shared command center object.

This method starts the delivery of remote control events using the responder chain. Remote-control events originate as commands issued by headsets and external accessories that are intended to control multimedia presented by an app. To stop the reception of remote-control events, you must call endReceivingRemoteControlEvents.

Availability

Available in iOS 4.0 and later.
endReceivingRemoteControlEvents() - endReceivingRemoteControlEvents

Tells the app to stop receiving remote-control events.

Declaration

Swift

func endReceivingRemoteControlEvents()

Objective-C

- (void)endReceivingRemoteControlEvents

Discussion

In iOS 7.1 and later, use the shared MPRemoteCommandCenter object to unregister for remote control events. You do not need to call this method when using the shared command center object.

This method stops the delivery of remote control events using the responder chain. Remote-control events originate as commands issued by headsets and external accessories that are intended to control multimedia presented by an app.

Availability

Available in iOS 4.0 and later.

See Also

– beginReceivingRemoteControlEvents

Controlling App Appearance

statusBarFrame statusBarFrame Property

The frame rectangle defining the area of the status bar. (read-only)

Declaration

Swift

var statusBarFrame: CGRect { get }

Objective-C

@property(nonatomic, readonly) CGRect statusBarFrame

Discussion

The value of this property is CGRectZero if the status bar is hidden.

Availability

Available in iOS 2.0 and later.

See Also

statusBarHidden
statusBarStyle
networkActivityIndicatorVisible networkActivityIndicatorVisible Property

A Boolean value that turns an indicator of network activity on or off.

Declaration

Swift

var networkActivityIndicatorVisible: Bool

Objective-C

@property(nonatomic, getter=isNetworkActivityIndicatorVisible) BOOL networkActivityIndicatorVisible

Discussion

Specify YEStrue if the app should show network activity and NOfalse if it should not. The default value is NOfalse. A spinning indicator in the status bar shows network activity. The app may explicitly hide or show this indicator.

Availability

Available in iOS 2.0 and later.
applicationIconBadgeNumber applicationIconBadgeNumber Property

The number currently set as the badge of the app icon in Springboard.

Declaration

Swift

var applicationIconBadgeNumber: Int

Objective-C

@property(nonatomic) NSInteger applicationIconBadgeNumber

Discussion

Set to 0 (zero) to hide the badge number. The default value of this property is 0.

Availability

Available in iOS 2.0 and later.
userInterfaceLayoutDirection userInterfaceLayoutDirection Property

Returns the layout direction of the user interface. (read-only)

Declaration

Swift

var userInterfaceLayoutDirection: UIUserInterfaceLayoutDirection { get }

Objective-C

@property(nonatomic, readonly) UIUserInterfaceLayoutDirection userInterfaceLayoutDirection

Discussion

This method specifies the general user interface layout flow direction. See UIUserInterfaceLayoutDirection for a description of the constants returned by this property.

Availability

Available in iOS 5.0 and later.

Getting the Font Sizing Preference

preferredContentSizeCategory preferredContentSizeCategory Property

The font sizing option preferred by the user. (read-only)

Declaration

Swift

var preferredContentSizeCategory: String { get }

Objective-C

@property(nonatomic, readonly) NSString *preferredContentSizeCategory

Discussion

Users can request that apps display fonts in a size that is larger or smaller than the normal font size defined by the system. For example, a user with a visual impairment might request a larger default font size to make it easier to read text. Font objects returned by the system automatically scale based on the user’s preference. You can use the value of this property to request a font object of the appropriate size.

When the value of this property changes, the app object sends a UIContentSizeCategoryDidChangeNotification notification so that observers can respond accordingly.

For a list of possible values, see Content Size Category Constants and Accessibility Content Size Category Constants.

Availability

Available in iOS 7.0 and later.

Managing the Default Interface Orientations

supportedInterfaceOrientationsForWindow(_:) - supportedInterfaceOrientationsForWindow:

Returns the default set of interface orientations to use for the view controllers in the specified window.

Declaration

Swift

func supportedInterfaceOrientationsForWindow(_ window: UIWindow?) -> UIInterfaceOrientationMask

Objective-C

- (UIInterfaceOrientationMask)supportedInterfaceOrientationsForWindow:(UIWindow *)window

Parameters

window

The window whose default interface orientations you want to retrieve.

Return Value

A bit mask specifying which orientations are supported. See UIInterfaceOrientationMask for valid bit-mask values. The value returned by this method must not be 0.

Discussion

Starting in iOS 8, you should employ the UITraitCollection and UITraitEnvironment APIs, and size class properties as used in those APIs, instead of using this method or otherwise writing your app in terms of interface orientation.

This method returns the default interface orientations for the app. These orientations are used only for view controllers that do not specify their own. If your app delegate implements the application:supportedInterfaceOrientationsForWindow: method, the system does not call this method.

The default implementation of this method returns the app’s default set of supported interface orientations, as you define them in the UISupportedInterfaceOrientations key of the Info.plist file in your Xcode project. If the file does not contain that key, this method returns all interface orientations for the iPad idiom and returns all interface orientations except the portrait upside-down orientation for the iPhone idiom.

Availability

Available in iOS 6.0 and later.

Managing Status Bar Orientation

statusBarOrientationAnimationDuration statusBarOrientationAnimationDuration Property

The animation duration in seconds for the status bar during a 90 degree orientation change. (read-only)

Declaration

Swift

var statusBarOrientationAnimationDuration: NSTimeInterval { get }

Objective-C

@property(nonatomic, readonly) NSTimeInterval statusBarOrientationAnimationDuration

Discussion

You should double the value of this property for a 180 degree orientation change in the status bar.

Availability

Available in iOS 2.0 and later.

See Also

– setStatusBarOrientation:animated:

Deprecated Methods

setNewsstandIconImage(_:) - setNewsstandIconImage: (iOS 9.0)

Sets the icon of a Newsstand app to an image depicting the current issue of a publication.

Declaration

Swift

func setNewsstandIconImage(_ image: UIImage?)

Objective-C

- (void)setNewsstandIconImage:(UIImage *)image

Parameters

image

An image to use as the icon of a Newsstand app. Pass nil to clear the currently set image and revert to the icon stored in the app bundle.

Discussion

The Newsstand app icon is typically downloaded from the app’s server for each issue.

Availability

Available in iOS 9.0 and later.

Deprecated in iOS 9.0.


    
      
           setKeepAliveTimeout(_:handler:)
      
      
           - setKeepAliveTimeout:handler:

(iOS 9.0)

Configures a periodic handler for VoIP apps in older versions of iOS.

Declaration

Swift

func setKeepAliveTimeout(_ timeout: NSTimeInterval, handler keepAliveHandler: (() -> Void)?) -> Bool

Objective-C

- (BOOL)setKeepAliveTimeout:(NSTimeInterval)timeout handler:(void (^)(void))keepAliveHandler

Parameters

`timeout`	The maximum interval (measured in seconds) at which your app should be woken up to check its VoIP connection. The minimum acceptable timeout value is 600 seconds.
`keepAliveHandler`	A block that performs the tasks needed to maintain your VoIP network connection. Setting this parameter to `nil` releases the current handler block and prevents UIKit from scheduling the next wake.

Return Value

YEStrue if the handler was installed or NOfalse if it was not.

Discussion

In iOS 8 and later, voice-over-IP (VoIP) apps register for registerForRemoteNotifications remote notifications instead of using this method. Using remote notifications eliminates the need for a timeout handler to check in with the VoIP service. Instead, when a calls arrives for the user, the VoIP service sends a VoIP remote notification to the user’s device. Upon receiving this notification, the device launches or wakes the app as needed so that it can handle the incoming call.

In iOS 7 and earlier, VoIP apps use this method to install a handler whose job is to maintain the app’s network connection with a VoIP server. This handler is guaranteed to be called before the specified timeout value but may be called at a slightly different time interval in order to better align execution of your handler with other system tasks, and thereby save power. Your handler has a maximum of 10 seconds to perform any needed tasks and exit. If it does not exit before time expires, the app is suspended.

Timeout values and handlers are not persisted between app launches. Therefore, if your app is terminated for any reason, you must reinstall the handler during the next launch cycle.

For calls to this method to succeed, the app must have the voip value in the array associated with the UIBackgroundModes key in its Info.plist file. Calling this method replaces the previously installed handler and timeout values, if any.

Availability

Available in iOS 4.0 and later.

Deprecated in iOS 9.0.

clearKeepAliveTimeout() - clearKeepAliveTimeout (iOS 9.0)

Removes a previously installed periodic handler block.

Declaration

Swift

func clearKeepAliveTimeout()

Objective-C

- (void)clearKeepAliveTimeout

Discussion

If your VoIP app no longer needs to be woken up at periodic intervals, you can use this method to remove any previously installed handler.

Availability

Available in iOS 4.0 and later.

Deprecated in iOS 9.0.


    
      
           setStatusBarHidden(_:withAnimation:)
      
      
           - setStatusBarHidden:withAnimation:

(iOS 9.0)

Hides or shows the status bar, optionally animating the transition.

Declaration

Swift

func setStatusBarHidden(_ hidden: Bool, withAnimation animation: UIStatusBarAnimation)

Objective-C

- (void)setStatusBarHidden:(BOOL)hidden withAnimation:(UIStatusBarAnimation)animation

Parameters

`hidden`	`YEStrue` to hide the status bar, `NOfalse` to show the status bar.
`animation`	A constant that indicates whether there should be an animation and, if one is requested, whether it should fade the status bar in or out or whether it should slide the status bar in or out.

Discussion

See the descriptions of the constants of the UIStatusBarAnimation type for more information.

Availability

Available in iOS 3.2 and later.

Deprecated in iOS 9.0.

statusBarHidden statusBarHidden (iOS 9.0) Property

A Boolean value that determines whether the status bar is hidden.

Declaration

Swift

var statusBarHidden: Bool

Objective-C

@property(readonly, nonatomic, getter=isStatusBarHidden) BOOL statusBarHidden

Return Value

YEStrue means the status bar is hidden; NOfalse means it's visible.

Discussion

Changing the value of this property changes the visibility of the status bar immediately—that is, without animations.

Availability

Available in iOS 2.0 and later.

Deprecated in iOS 9.0.

See Also

– setStatusBarHidden:animated:


    
      
           setStatusBarStyle(_:animated:)
      
      
           - setStatusBarStyle:animated:

(iOS 9.0)

Sets the style of the status bar, optionally animating the transition to the new style.

Declaration

Swift

func setStatusBarStyle(_ statusBarStyle: UIStatusBarStyle, animated animated: Bool)

Objective-C

- (void)setStatusBarStyle:(UIStatusBarStyle)statusBarStyle animated:(BOOL)animated

Parameters

`statusBarStyle`	A constant that specifies a style for the status bar. See the descriptions of the constants in UIStatusBarStyle for details.
`animated`	`YEStrue` if the transition to the new style should be animated; otherwise `NOfalse` .

Discussion

The animation slides the status bar out toward the top of the interface.

In iOS 7 and later, status bar behavior is determined by view controllers, and so calling this method has no effect by default. When view controller-based status bar appearance is disabled, this method behaves normally. To opt out of the view controller-based status bar appearance behavior, you must add the UIViewControllerBasedStatusBarAppearance key with a value of NOfalse to your app’s Info.plist file, but doing so is not recommended.

Availability

Available in iOS 2.0 and later.

Deprecated in iOS 9.0.

Declaration

Swift

func setStatusBarOrientation(_ interfaceOrientation: UIInterfaceOrientation, animated animated: Bool)

Objective-C

- (void)setStatusBarOrientation:(UIInterfaceOrientation)interfaceOrientation animated:(BOOL)animated

Parameters

`interfaceOrientation`	A specific orientation of the status bar. See UIInterfaceOrientation for details. The default value is `UIInterfaceOrientationPortrait`.
`animated`	`YEStrue` if the transition to the new orientation should be animated; `NOfalse` if it should be immediate, without animation.

Discussion

Calling this method changes the value of the statusBarOrientation property and rotates the status bar, animating the transition if animated is YEStrue . If your app has rotatable window content, however, you should not arbitrarily set status-bar orientation using this method. The status-bar orientation set by this method does not change if the device changes orientation.

Availability

Available in iOS 2.0 and later.

Deprecated in iOS 9.0.

Deprecation Statement

Use the setStatusBarHidden:withAnimation: method instead.

Declaration

Objective-C

- (void)setStatusBarHidden:(BOOL)hidden animated:(BOOL)animated

Parameters

`hidden`	`YEStrue` if the status bar should be hidden, `NOfalse` if it should be visible. The default value is `NOfalse`.
`animated`	`YEStrue` if the transition to or from a hidden state should be animated, `NOfalse` otherwise.

Discussion

The animation fades the status bar out or in at the top of the interface, depending on the value of hidden.

Availability

Available in iOS 2.0 and later.

Deprecated in iOS 3.2.

Data Types

UIBackgroundTaskIdentifier UIBackgroundTaskIdentifier

A unique token that identifies a request to run in the background.

Declaration

Swift

typealias UIBackgroundTaskIdentifier = Int

Objective-C

typedef NSUInteger UIBackgroundTaskIdentifier;

Import Statement

Objective-C

@import UIKit;

Swift

import UIKit

Availability

Available in iOS 4.0 and later.
UIRemoteNotificationType UIRemoteNotificationType
Constants indicating the types of notifications the app may display to the user.

Register for user notification settings using the registerUserNotificationSettings: method instead.

Declaration

Swift

struct UIRemoteNotificationType : OptionSetType { init(rawValue rawValue: UInt) static var None: UIRemoteNotificationType { get } static var Badge: UIRemoteNotificationType { get } static var Sound: UIRemoteNotificationType { get } static var Alert: UIRemoteNotificationType { get } static var NewsstandContentAvailability: UIRemoteNotificationType { get } }

Objective-C

typedef enum : NSUInteger { UIRemoteNotificationTypeNone = 0, UIRemoteNotificationTypeBadge = 1 << 0, UIRemoteNotificationTypeSound = 1 << 1, UIRemoteNotificationTypeAlert = 1 << 2, UIRemoteNotificationTypeNewsstandContentAvailability = 1 << 3 } UIRemoteNotificationType;

Constants
- None
  
  UIRemoteNotificationTypeNone
  
  The app accepts no notifications.
  Register for user notification settings using the registerUserNotificationSettings: method instead
  
  Available in iOS 3.0 and later.
  
  Deprecated in iOS 8.0.
- Badge
  
  UIRemoteNotificationTypeBadge
  
  The app accepts notifications that badge the app icon.
  Register for user notification settings using the registerUserNotificationSettings: method instead
  
  Available in iOS 3.0 and later.
  
  Deprecated in iOS 8.0.
- Sound
  
  UIRemoteNotificationTypeSound
  
  The app accepts alert sounds as notifications.
  Register for user notification settings using the registerUserNotificationSettings: method instead
  
  Available in iOS 3.0 and later.
  
  Deprecated in iOS 8.0.
- Alert
  
  UIRemoteNotificationTypeAlert
  
  The app accepts alert messages as notifications.
  Register for user notification settings using the registerUserNotificationSettings: method instead
  
  Available in iOS 3.0 and later.
  
  Deprecated in iOS 8.0.
- NewsstandContentAvailability
  
  UIRemoteNotificationTypeNewsstandContentAvailability
  
  The app accepts notifications that start the downloading of issue assets for Newsstand apps.
  Register for user notification settings using the registerUserNotificationSettings: method instead
  
  Available in iOS 3.0 and later.
  
  Deprecated in iOS 8.0.
Discussion

One or more of the values in the UIRemoteNotificationType bit mask are passed to iOS as the argument of the registerForRemoteNotificationTypes: method. Thereafter, iOS filters notifications for the app based on these values. You can always get the current notification types by calling the enabledRemoteNotificationTypes method.

Import Statement

Objective-C

@import UIKit;

Swift

import UIKit

Availability

Available in iOS 3.0 and later.
UIStatusBarStyle UIStatusBarStyle
The style of the device’s status bar.

Declaration

Swift

enum UIStatusBarStyle : Int { case Default case LightContent static var BlackTranslucent: UIStatusBarStyle { get } case BlackOpaque }

Objective-C

typedef enum : NSInteger { UIStatusBarStyleDefault, UIStatusBarStyleLightContent, UIStatusBarStyleBlackTranslucent, UIStatusBarStyleBlackOpaque } UIStatusBarStyle;

Constants
- Default
  
  UIStatusBarStyleDefault
  
  A dark status bar, intended for use on light backgrounds.
  
  Available in iOS 2.0 and later.
- LightContent
  
  UIStatusBarStyleLightContent
  
  A light status bar, intended for use on dark backgrounds.
  
  Available in iOS 7.0 and later.
- UIStatusBarStyleBlackTranslucent
  
  A transparent black style.
  
  Use UIStatusBarStyleLightContent instead.
  
  Available in iOS 2.0 and later.
  
  Deprecated in iOS 7.0.
- UIStatusBarStyleBlackOpaque
  
  An opaque black style.
  
  Use UIStatusBarStyleLightContent instead.
  
  Available in iOS 2.0 and later.
  
  Deprecated in iOS 7.0.
Import Statement

Objective-C

@import UIKit;

Swift

import UIKit

Availability

Available in iOS 2.0 and later.
UIStatusBarAnimation UIStatusBarAnimation
The animation applied to the status bar as it is hidden or made visible.

Declaration

Swift

enum UIStatusBarAnimation : Int { case None case Fade case Slide }

Objective-C

typedef enum : NSInteger { UIStatusBarAnimationNone, UIStatusBarAnimationFade, UIStatusBarAnimationSlide, } UIStatusBarAnimation;

Constants
- None
  
  UIStatusBarAnimationNone
  
  No animation is applied to the status bar as it is shown or hidden.
  
  Available in iOS 3.2 and later.
- Fade
  
  UIStatusBarAnimationFade
  
  The status bar fades in and out as it is shown or hidden, respectively.
  
  Available in iOS 3.2 and later.
- Slide
  
  UIStatusBarAnimationSlide
  
  The status bar slides in or out as it is shown or hidden, respectively.
  
  Available in iOS 3.2 and later.
Discussion

Constants of the UIStatusBarAnimation type are arguments of the setStatusBarHidden:withAnimation: method.

Import Statement

Objective-C

@import UIKit;

Swift

import UIKit

Availability

Available in iOS 3.2 and later.

Constants

UIApplicationState
The running states of an app

Declaration

Swift

enum UIApplicationState : Int { case Active case Inactive case Background }

Objective-C

typedef enum : NSInteger { UIApplicationStateActive, UIApplicationStateInactive, UIApplicationStateBackground } UIApplicationState;

Constants
- Active
  
  UIApplicationStateActive
  
  The app is running in the foreground and currently receiving events.
  
  Available in iOS 4.0 and later.
- Inactive
  
  UIApplicationStateInactive
  
  The app is running in the foreground but is not receiving events. This might happen as a result of an interruption or because the app is transitioning to or from the background.
  
  Available in iOS 4.0 and later.
- Background
  
  UIApplicationStateBackground
  
  The app is running in the background.
  
  Available in iOS 4.0 and later.
Import Statement

Objective-C

@import UIKit;

Swift

import UIKit

Availability

Available in iOS 4.0 and later.
Background Task Constants
Constants used when running in the background.

Declaration

Swift

let UIBackgroundTaskInvalid: UIBackgroundTaskIdentifier let UIMinimumKeepAliveTimeout: NSTimeInterval

Objective-C

const UIBackgroundTaskIdentifier UIBackgroundTaskInvalid; const NSTimeInterval UIMinimumKeepAliveTimeout;

Constants
- UIBackgroundTaskInvalid
  
  UIBackgroundTaskInvalid
  
  An token indicating an invalid task request. This constant should be used to initialize variables or to check for errors.
  
  Available in iOS 4.0 and later.
- UIMinimumKeepAliveTimeout
  
  UIMinimumKeepAliveTimeout
  
  The minimum amount of time (measured in seconds) an app may run a critical background task in the background.
  
  Available in iOS 4.0 and later.
UIBackgroundFetchResult
Constants that indicate the result of a background fetch operation.

Declaration

Swift

enum UIBackgroundFetchResult : UInt { case NewData case NoData case Failed }

Objective-C

typedef enum : NSUInteger { UIBackgroundFetchResultNewData, UIBackgroundFetchResultNoData, UIBackgroundFetchResultFailed } UIBackgroundFetchResult;

Constants
- NewData
  
  UIBackgroundFetchResultNewData
  
  New data was successfully downloaded.
  
  Available in iOS 7.0 and later.
- NoData
  
  UIBackgroundFetchResultNoData
  
  There was no new data to download.
  
  Available in iOS 7.0 and later.
- Failed
  
  UIBackgroundFetchResultFailed
  
  An attempt to download data was made but that attempt failed.
  
  Available in iOS 7.0 and later.
Import Statement

Objective-C

@import UIKit;

Swift

import UIKit

Availability

Available in iOS 7.0 and later.
Fetch Intervals
Constants indicating fetch intervals for background downloads.

Declaration

Swift

let UIApplicationBackgroundFetchIntervalMinimum: NSTimeInterval let UIApplicationBackgroundFetchIntervalNever: NSTimeInterval

Objective-C

const NSTimeInterval UIApplicationBackgroundFetchIntervalMinimum; const NSTimeInterval UIApplicationBackgroundFetchIntervalNever;

Constants
- UIApplicationBackgroundFetchIntervalMinimum
  
  UIApplicationBackgroundFetchIntervalMinimum
  
  The smallest fetch interval supported by the system.
  
  Available in iOS 7.0 and later.
- UIApplicationBackgroundFetchIntervalNever
  
  UIApplicationBackgroundFetchIntervalNever
  
  A fetch interval large enough to prevent fetch operations from occurring.
  
  Available in iOS 7.0 and later.
UIBackgroundRefreshStatus
Constants indicating whether background execution is enabled for the app.

Declaration

Swift

enum UIBackgroundRefreshStatus : Int { case Restricted case Denied case Available }

Objective-C

typedef enum : NSUInteger { UIBackgroundRefreshStatusRestricted, UIBackgroundRefreshStatusDenied, UIBackgroundRefreshStatusAvailable } UIBackgroundRefreshStatus;

Constants
- Restricted
  
  UIBackgroundRefreshStatusRestricted
  
  Background updates are unavailable and the user cannot enable them again. For example, this status can occur when parental controls are in effect for the current user.
  
  Available in iOS 7.0 and later.
- Denied
  
  UIBackgroundRefreshStatusDenied
  
  The user explicitly disabled background behavior for this app or for the whole system.
  
  Available in iOS 7.0 and later.
- Available
  
  UIBackgroundRefreshStatusAvailable
  
  Background updates are available for the app.
  
  Available in iOS 7.0 and later.
Import Statement

Objective-C

@import UIKit;

Swift

import UIKit

Availability

Available in iOS 7.0 and later.
UIInterfaceOrientation
The orientation of the app's user interface.

Declaration

Swift

enum UIInterfaceOrientation : Int { case Unknown case Portrait case PortraitUpsideDown case LandscapeLeft case LandscapeRight }

Objective-C

typedef enum : NSInteger { UIInterfaceOrientationUnknown = UIDeviceOrientationUnknown, UIInterfaceOrientationPortrait = UIDeviceOrientationPortrait, UIInterfaceOrientationPortraitUpsideDown = UIDeviceOrientationPortraitUpsideDown, UIInterfaceOrientationLandscapeLeft = UIDeviceOrientationLandscapeRight, UIInterfaceOrientationLandscapeRight = UIDeviceOrientationLandscapeLeft } UIInterfaceOrientation;

Constants
- Unknown
  
  UIInterfaceOrientationUnknown
  
  The orientation of the device cannot be determined.
  
  Available in iOS 8.0 and later.
- Portrait
  
  UIInterfaceOrientationPortrait
  
  The device is in portrait mode, with the device held upright and the home button on the bottom.
  
  Available in iOS 2.0 and later.
- PortraitUpsideDown
  
  UIInterfaceOrientationPortraitUpsideDown
  
  The device is in portrait mode but upside down, with the device held upright and the home button at the top.
  
  Available in iOS 2.0 and later.
- LandscapeLeft
  
  UIInterfaceOrientationLandscapeLeft
  
  The device is in landscape mode, with the device held upright and the home button on the left side.
  
  Available in iOS 2.0 and later.
- LandscapeRight
  
  UIInterfaceOrientationLandscapeRight
  
  The device is in landscape mode, with the device held upright and the home button on the right side.
  
  Available in iOS 2.0 and later.
Discussion

Starting in iOS 8, you should employ the UITraitCollection and UITraitEnvironment APIs, and size class properties as used in those APIs, instead of using UIInterfaceOrientation constants or otherwise writing your app in terms of interface orientation.

In earlier versions of iOS, you used these constants in the statusBarOrientation property and the setStatusBarOrientation:animated: method. Notice that UIDeviceOrientationLandscapeRightis assigned to UIInterfaceOrientationLandscapeLeft and UIDeviceOrientationLandscapeLeft is assigned to UIInterfaceOrientationLandscapeRight; the reason for this is that rotating the device requires rotating the content in the opposite direction.

Import Statement

Objective-C

@import UIKit;

Swift

import UIKit

Availability

Available in iOS 2.0 and later.
UIInterfaceOrientationMask
These constants are mask bits for specifying a view controller’s supported interface orientations.

Declaration

Swift

struct UIInterfaceOrientationMask : OptionSetType { init(rawValue rawValue: UInt) static var Portrait: UIInterfaceOrientationMask { get } static var LandscapeLeft: UIInterfaceOrientationMask { get } static var LandscapeRight: UIInterfaceOrientationMask { get } static var PortraitUpsideDown: UIInterfaceOrientationMask { get } static var Landscape: UIInterfaceOrientationMask { get } static var All: UIInterfaceOrientationMask { get } static var AllButUpsideDown: UIInterfaceOrientationMask { get } }

Objective-C

typedef enum : NSUInteger { UIInterfaceOrientationMaskPortrait = (1 << UIInterfaceOrientationPortrait ), UIInterfaceOrientationMaskLandscapeLeft = (1 << UIInterfaceOrientationLandscapeLeft ), UIInterfaceOrientationMaskLandscapeRight = (1 << UIInterfaceOrientationLandscapeRight ), UIInterfaceOrientationMaskPortraitUpsideDown = (1 << UIInterfaceOrientationPortraitUpsideDown ), UIInterfaceOrientationMaskLandscape = (UIInterfaceOrientationMaskLandscapeLeft | UIInterfaceOrientationMaskLandscapeRight ), UIInterfaceOrientationMaskAll = (UIInterfaceOrientationMaskPortrait | UIInterfaceOrientationMaskLandscapeLeft | UIInterfaceOrientationMaskLandscapeRight | UIInterfaceOrientationMaskPortraitUpsideDown ), UIInterfaceOrientationMaskAllButUpsideDown = (UIInterfaceOrientationMaskPortrait | UIInterfaceOrientationMaskLandscapeLeft | UIInterfaceOrientationMaskLandscapeRight ), } UIInterfaceOrientationMask;

Constants
- Portrait
  
  UIInterfaceOrientationMaskPortrait
  
  The view controller supports a portrait interface orientation.
  
  Available in iOS 6.0 and later.
- LandscapeLeft
  
  UIInterfaceOrientationMaskLandscapeLeft
  
  The view controller supports a landscape-left interface orientation.
  
  Available in iOS 6.0 and later.
- LandscapeRight
  
  UIInterfaceOrientationMaskLandscapeRight
  
  The view controller supports a landscape-right interface orientation.
  
  Available in iOS 6.0 and later.
- PortraitUpsideDown
  
  UIInterfaceOrientationMaskPortraitUpsideDown
  
  The view controller supports an upside-down portrait interface orientation.
  
  Available in iOS 6.0 and later.
- Landscape
  
  UIInterfaceOrientationMaskLandscape
  
  The view controller supports both landscape-left and landscape-right interface orientation.
  
  Available in iOS 6.0 and later.
- All
  
  UIInterfaceOrientationMaskAll
  
  The view controller supports all interface orientations.
  
  Available in iOS 6.0 and later.
- AllButUpsideDown
  
  UIInterfaceOrientationMaskAllButUpsideDown
  
  The view controller supports all but the upside-down portrait interface orientation.
  
  Available in iOS 6.0 and later.
Discussion

Starting in iOS 8, you should employ the UITraitCollection and UITraitEnvironment APIs, and size class properties as used in those APIs, instead of using UIInterfaceOrientation constants or otherwise writing your app in terms of interface orientation.

In earlier versions of iOS, you returned these constants from the supportedInterfaceOrientationsForWindow: method or when determining which orientations to support in your app’s view controllers.

Import Statement

Objective-C

@import UIKit;

Swift

import UIKit

Availability

Available in iOS 6.0 and later.
UIUserInterfaceLayoutDirection
Specifies the directional flow of the user interface.

Declaration

Swift

enum UIUserInterfaceLayoutDirection : Int { case LeftToRight case RightToLeft }

Objective-C

typedef enum : NSInteger { UIUserInterfaceLayoutDirectionLeftToRight, UIUserInterfaceLayoutDirectionRightToLeft, } UIUserInterfaceLayoutDirection;

Constants
- LeftToRight
  
  UIUserInterfaceLayoutDirectionLeftToRight
  
  The layout direction is left to right.
  
  Available in iOS 5.0 and later.
- RightToLeft
  
  UIUserInterfaceLayoutDirectionRightToLeft
  
  The layout direction right to left. This value is appropriate when running with localizations such as Arabic or Hebrew that should have the user interface layout origin on the right edge of the coordinate system.
  
  Available in iOS 5.0 and later.
Discussion

One of these constants is returned by the userInterfaceLayoutDirection property. It indicates the directionality of the language in the user interface of the app.

Import Statement

Objective-C

@import UIKit;

Swift

import UIKit

Availability

Available in iOS 5.0 and later.
Settings Launch URL
Constant used to open the app’s settings.

Declaration

Swift

let UIApplicationOpenSettingsURLString: String

Objective-C

NSString *const UIApplicationOpenSettingsURLString;

Constants
- UIApplicationOpenSettingsURLString
  
  UIApplicationOpenSettingsURLString
  
  Used to create a URL that you can pass to the openURL: method. When you open the URL built from this string, the system launches the Settings app and displays the app’s custom settings, if it has any.
  
  Available in iOS 8.0 and later.
UserInfo Dictionary Keys
Keys used to access values in the userInfo dictionary of some UIApplication-posted notifications.

Declaration

Swift

let UIApplicationStatusBarOrientationUserInfoKey: String let UIApplicationStatusBarFrameUserInfoKey: String

Objective-C

NSString *const UIApplicationStatusBarOrientationUserInfoKey; NSString *const UIApplicationStatusBarFrameUserInfoKey;

Constants
- UIApplicationStatusBarOrientationUserInfoKey
  
  UIApplicationStatusBarOrientationUserInfoKey
  
  A key whose value is an NSNumber object that encapsulates a UIInterfaceOrientation value indicating the current orientation (see UIInterfaceOrientation). This key is used with UIApplicationDidChangeStatusBarOrientationNotification and UIApplicationWillChangeStatusBarOrientationNotification notifications.
  
  Available in iOS 2.0 and later.
- UIApplicationStatusBarFrameUserInfoKey
  
  UIApplicationStatusBarFrameUserInfoKey
  
  A key whose value is an NSValue object that encapsulates a CGRect structure expressing the location and size of the new status bar frame. This key is used with UIApplicationDidChangeStatusBarFrameNotification and UIApplicationWillChangeStatusBarFrameNotification notifications.
  
  Available in iOS 2.0 and later.
Content Size Category Constants
Constants that indicate the user’s preferred font size.

Declaration

Swift

let UIContentSizeCategoryExtraSmall: String let UIContentSizeCategorySmall: String let UIContentSizeCategoryMedium: String let UIContentSizeCategoryLarge: String let UIContentSizeCategoryExtraLarge: String let UIContentSizeCategoryExtraExtraLarge: String let UIContentSizeCategoryExtraExtraExtraLarge: String

Objective-C

NSString *const UIContentSizeCategoryExtraSmall; NSString *const UIContentSizeCategorySmall; NSString *const UIContentSizeCategoryMedium; NSString *const UIContentSizeCategoryLarge; NSString *const UIContentSizeCategoryExtraLarge; NSString *const UIContentSizeCategoryExtraExtraLarge; NSString *const UIContentSizeCategoryExtraExtraExtraLarge;

Constants
- UIContentSizeCategoryExtraSmall
  
  UIContentSizeCategoryExtraSmall
  
  An extra small font.
  
  Available in iOS 7.0 and later.
- UIContentSizeCategorySmall
  
  UIContentSizeCategorySmall
  
  A small font.
  
  Available in iOS 7.0 and later.
- UIContentSizeCategoryMedium
  
  UIContentSizeCategoryMedium
  
  A medium-sized font.
  
  Available in iOS 7.0 and later.
- UIContentSizeCategoryLarge
  
  UIContentSizeCategoryLarge
  
  A large font.
  
  Available in iOS 7.0 and later.
- UIContentSizeCategoryExtraLarge
  
  UIContentSizeCategoryExtraLarge
  
  An extra large font.
  
  Available in iOS 7.0 and later.
- UIContentSizeCategoryExtraExtraLarge
  
  UIContentSizeCategoryExtraExtraLarge
  
  An increasingly large font.
  
  Available in iOS 7.0 and later.
- UIContentSizeCategoryExtraExtraExtraLarge
  
  UIContentSizeCategoryExtraExtraExtraLarge
  
  The largest font option.
  
  Available in iOS 7.0 and later.
Accessibility Content Size Category Constants
Constants that indicate the preferred font sizes when accessibility is enabled.

Declaration

Swift

let UIContentSizeCategoryAccessibilityMedium: String let UIContentSizeCategoryAccessibilityLarge: String let UIContentSizeCategoryAccessibilityExtraLarge: String let UIContentSizeCategoryAccessibilityExtraExtraLarge: String let UIContentSizeCategoryAccessibilityExtraExtraExtraLarge: String

Objective-C

NSString *const UIContentSizeCategoryAccessibilityMedium; NSString *const UIContentSizeCategoryAccessibilityLarge; NSString *const UIContentSizeCategoryAccessibilityExtraLarge; NSString *const UIContentSizeCategoryAccessibilityExtraExtraLarge; NSString *const UIContentSizeCategoryAccessibilityExtraExtraExtraLarge;

Constants
- UIContentSizeCategoryAccessibilityMedium
  
  UIContentSizeCategoryAccessibilityMedium
  
  A medium font size reflecting the current accessibility settings.
  
  Available in iOS 7.0 and later.
- UIContentSizeCategoryAccessibilityLarge
  
  UIContentSizeCategoryAccessibilityLarge
  
  A large font size reflecting the current accessibility settings.
  
  Available in iOS 7.0 and later.
- UIContentSizeCategoryAccessibilityExtraLarge
  
  UIContentSizeCategoryAccessibilityExtraLarge
  
  A medium font size reflecting the current accessibility settings.
  
  Available in iOS 7.0 and later.
- UIContentSizeCategoryAccessibilityExtraExtraLarge
  
  UIContentSizeCategoryAccessibilityExtraExtraLarge
  
  A medium font size reflecting the current accessibility settings.
  
  Available in iOS 7.0 and later.
- UIContentSizeCategoryAccessibilityExtraExtraExtraLarge
  
  UIContentSizeCategoryAccessibilityExtraExtraExtraLarge
  
  A medium font size reflecting the current accessibility settings.
  
  Available in iOS 7.0 and later.
Key for Content Size Change Notifications
Key identifying the new content size category.

Declaration

Swift

let UIContentSizeCategoryNewValueKey: String

Objective-C

NSString *const UIContentSizeCategoryNewValueKey;

Constants
- UIContentSizeCategoryNewValueKey
  
  UIContentSizeCategoryNewValueKey
  
  A key whose value is an NSString object reflecting the new value of the preferredContentSizeCategory property.
  
  Available in iOS 7.0 and later.
Extension Point Identifier Constants
Constants that identify extension points you want to disallow in your app.

Declaration

Swift

let UIApplicationKeyboardExtensionPointIdentifier: String

Objective-C

NSString *const UIApplicationKeyboardExtensionPointIdentifier;

Constants
- UIApplicationKeyboardExtensionPointIdentifier
  
  UIApplicationKeyboardExtensionPointIdentifier
  
  The identifier for custom keyboards. To reject the use of custom keyboards in your app, specify this constant in your implementation of the application:shouldAllowExtensionPointIdentifier: delegate method.
  
  Available in iOS 8.0 and later.
Discussion

In iOS 8.0, the only app extension type you can disallow is the custom keyboard.
Run Loop Mode for Tracking
Mode while tracking in controls is taking place.

Declaration

Swift

let UITrackingRunLoopMode: String

Objective-C

UIKIT_EXTERN NSString *UITrackingRunLoopMode;

Constants
- UITrackingRunLoopMode
  
  UITrackingRunLoopMode
  
  The mode set while tracking in controls takes place. You can use this mode to add timers that fire during tracking.
  
  Available in iOS 2.0 and later.
Exceptions
The following constant defines an exception that can be thrown by the app.

Declaration

Swift

let UIApplicationInvalidInterfaceOrientationException: String

Objective-C

NSString *const UIApplicationInvalidInterfaceOrientationException;

Constants
- UIApplicationInvalidInterfaceOrientationException
  
  UIApplicationInvalidInterfaceOrientationException
  
  This exception is thrown if a view controller or the app returns 0 instead of a valid set of supported interface orientation values. It is also thrown if the orientation returned by a view controller’s preferredInterfaceOrientationForPresentation method does not match one of the view controller’s supported orientations.
  
  Available in iOS 6.0 and later.

Notifications

UIApplicationBackgroundRefreshStatusDidChangeNotification UIApplicationBackgroundRefreshStatusDidChangeNotification

Posted when the app’s status for downloading content in the background changes.
The system sends this notification when the backgroundRefreshStatus property of the app object changes. That property can change in response to the user disabling multitasking support for the app. The object of the notification is the UIApplication object. There is no userInfo dictionary.

Declaration

Swift

let UIApplicationBackgroundRefreshStatusDidChangeNotification: String

Import Statement

Objective-C

@import UIKit;

Swift

import UIKit

Availability

Available in iOS 7.0 and later.
UIApplicationDidBecomeActiveNotification UIApplicationDidBecomeActiveNotification

Posted when the app becomes active.
An app is active when it is receiving events. An active app can be said to have focus. It gains focus after being launched, loses focus when an overlay window pops up or when the device is locked, and gains focus when the device is unlocked.

Declaration

Swift

let UIApplicationDidBecomeActiveNotification: String

Import Statement

Objective-C

@import UIKit;

Swift

import UIKit

Availability

Available in iOS 2.0 and later.
UIApplicationDidChangeStatusBarFrameNotification UIApplicationDidChangeStatusBarFrameNotification

Posted when the frame of the status bar changes.
The userInfo dictionary contains an NSValue object that encapsulates a CGRect structure expressing the location and size of the new status bar frame. Use UIApplicationStatusBarFrameUserInfoKey to access this value.

Declaration

Swift

let UIApplicationDidChangeStatusBarFrameNotification: String

Import Statement

Objective-C

@import UIKit;

Swift

import UIKit

Availability

Available in iOS 2.0 and later.
UIApplicationDidChangeStatusBarOrientationNotification UIApplicationDidChangeStatusBarOrientationNotification

Posted when the orientation of the app’s user interface changes.
The userInfo dictionary contains an NSNumber object that encapsulates a UIInterfaceOrientation value (see UIInterfaceOrientation). Use UIApplicationStatusBarOrientationUserInfoKey to access this value

Declaration

Swift

let UIApplicationDidChangeStatusBarOrientationNotification: String

Import Statement

Objective-C

@import UIKit;

Swift

import UIKit

Availability

Available in iOS 2.0 and later.
UIApplicationDidEnterBackgroundNotification UIApplicationDidEnterBackgroundNotification

Posted when the app enters the background.
The object of the notification is the UIApplication object. There is no userInfo dictionary.

Declaration

Swift

let UIApplicationDidEnterBackgroundNotification: String

Import Statement

Objective-C

@import UIKit;

Swift

import UIKit

Availability

Available in iOS 4.0 and later.
UIApplicationDidFinishLaunchingNotification UIApplicationDidFinishLaunchingNotification

Posted immediately after the app finishes launching.
If the app was launched as a result of in remote notification targeted at it or because another app opened a URL resource claimed the posting app (the notification object), this notification contains a userInfo dictionary. You can access the contents of the dictionary using the UIApplicationLaunchOptionsURLKey and UIApplicationLaunchOptionsSourceApplicationKey constants (for URLs), the UIApplicationLaunchOptionsRemoteNotificationKey constant (for remote notifications), and the UIApplicationLaunchOptionsLocalNotificationKey constant (for local notifications). If the notification was posted for a normal app launch, there is no userInfo dictionary.

Declaration

Swift

let UIApplicationDidFinishLaunchingNotification: String

Import Statement

Objective-C

@import UIKit;

Swift

import UIKit

Availability

Available in iOS 2.0 and later.
UIApplicationDidReceiveMemoryWarningNotification UIApplicationDidReceiveMemoryWarningNotification

Posted when the app receives a warning from the operating system about low memory availability.
This notification does not contain a userInfo dictionary.

Declaration

Swift

let UIApplicationDidReceiveMemoryWarningNotification: String

Import Statement

Objective-C

@import UIKit;

Swift

import UIKit

Availability

Available in iOS 2.0 and later.
UIApplicationProtectedDataDidBecomeAvailable UIApplicationProtectedDataDidBecomeAvailable

Posted when the protected files become available for your code to access.
This notification does not contain a userInfo dictionary.

Declaration

Swift

let UIApplicationProtectedDataDidBecomeAvailable: String

Import Statement

Objective-C

@import UIKit;

Swift

import UIKit

Availability

Available in iOS 4.0 and later.
UIApplicationProtectedDataWillBecomeUnavailable UIApplicationProtectedDataWillBecomeUnavailable

Posted shortly before protected files are locked down and become inaccessible.
Upon receiving this notification, clients should release any references to protected files. This notification does not contain a userInfo dictionary.

Declaration

Swift

let UIApplicationProtectedDataWillBecomeUnavailable: String

Import Statement

Objective-C

@import UIKit;

Swift

import UIKit

Availability

Available in iOS 4.0 and later.
UIApplicationSignificantTimeChangeNotification UIApplicationSignificantTimeChangeNotification

Posted when there is a significant change in time, for example, change to a new day (midnight), carrier time update, and change to or from daylight savings time.
This notification does not contain a userInfo dictionary.

Declaration

Swift

let UIApplicationSignificantTimeChangeNotification: String

Import Statement

Objective-C

@import UIKit;

Swift

import UIKit

Availability

Available in iOS 2.0 and later.
UIApplicationUserDidTakeScreenshotNotification UIApplicationUserDidTakeScreenshotNotification

Posted when the user presses the Home and Lock buttons to take a screenshot.
This notification does not contain a userInfo dictionary. This notification is posted after the screenshot is taken.

Declaration

Swift

let UIApplicationUserDidTakeScreenshotNotification: String

Import Statement

Objective-C

@import UIKit;

Swift

import UIKit

Availability

Available in iOS 7.0 and later.
UIApplicationWillChangeStatusBarOrientationNotification UIApplicationWillChangeStatusBarOrientationNotification

Posted when the app is about to change the orientation of its interface.
The userInfo dictionary contains an NSNumber that encapsulates a UIInterfaceOrientation value (see UIInterfaceOrientation). Use UIApplicationStatusBarOrientationUserInfoKey to access this value.

Declaration

Swift

let UIApplicationWillChangeStatusBarOrientationNotification: String

Import Statement

Objective-C

@import UIKit;

Swift

import UIKit

Availability

Available in iOS 2.0 and later.
UIApplicationWillChangeStatusBarFrameNotification UIApplicationWillChangeStatusBarFrameNotification

Posted when the app is about to change the frame of the status bar.
The userInfo dictionary contains an NSValue object that encapsulates a CGRect structure expressing the location and size of the new status bar frame. Use UIApplicationStatusBarFrameUserInfoKey to access this value.

Declaration

Swift

let UIApplicationWillChangeStatusBarFrameNotification: String

Import Statement

Objective-C

@import UIKit;

Swift

import UIKit

Availability

Available in iOS 2.0 and later.
UIApplicationWillEnterForegroundNotification UIApplicationWillEnterForegroundNotification

Posted shortly before an app leaves the background state on its way to becoming the active app.
The object of the notification is the UIApplication object. There is no userInfo dictionary.

Declaration

Swift

let UIApplicationWillEnterForegroundNotification: String

Import Statement

Objective-C

@import UIKit;

Swift

import UIKit

Availability

Available in iOS 4.0 and later.
UIApplicationWillResignActiveNotification UIApplicationWillResignActiveNotification

Posted when the app is no longer active and loses focus.
An app is active when it is receiving events. An active app can be said to have focus. It gains focus after being launched, loses focus when an overlay window pops up or when the device is locked, and gains focus when the device is unlocked.

Declaration

Swift

let UIApplicationWillResignActiveNotification: String

Import Statement

Objective-C

@import UIKit;

Swift

import UIKit

Availability

Available in iOS 2.0 and later.
UIApplicationWillTerminateNotification UIApplicationWillTerminateNotification

Posted when the app is about to terminate.
This notification is associated with the delegate applicationWillTerminate: method. This notification does not contain a userInfo dictionary.

Declaration

Swift

let UIApplicationWillTerminateNotification: String

Import Statement

Objective-C

@import UIKit;

Swift

import UIKit

Availability

Available in iOS 2.0 and later.
UIContentSizeCategoryDidChangeNotification UIContentSizeCategoryDidChangeNotification

Posted when the user changes the preferred content size setting.
This notification is sent when the value in the preferredContentSizeCategory property changes. The userInfo dictionary of the notification contains the UIContentSizeCategoryNewValueKey key, which reflects the new setting.

Declaration

Swift

let UIContentSizeCategoryDidChangeNotification: String

Import Statement

Objective-C

@import UIKit;

Swift

import UIKit

Availability

Available in iOS 7.0 and later.

UIApplication

Subclassing Notes

Getting the App Instance

Declaration

Return Value

Availability

Getting the App Delegate

Declaration

Discussion

Availability

Getting App Windows

Declaration

Discussion

Availability

See Also

Declaration

Discussion

Availability

See Also

Controlling and Handling Events

Declaration

Parameters

Discussion

Availability

See Also

Declaration

Parameters

Return Value

Discussion

Availability

See Also

Declaration

Discussion

Availability

See Also

Declaration

Discussion

Availability

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Declaration

Return Value

Availability

Declaration

Discussion

Availability

Opening a URL Resource

Declaration

Parameters

Return Value

Discussion

Availability

See Also

Declaration

Parameters

Return Value

Discussion

Availability

See Also

Configuring the User Notification Settings

Declaration

Parameters

Discussion

Availability

See Also

Declaration

Return Value

Discussion

Availability

See Also

Registering for Remote Notifications

Declaration

Discussion

Availability

See Also

Declaration

Discussion

Availability

See Also

Declaration

Return Value