UIKit Function Reference

Inherits From

Not Applicable

Conforms To

Not Applicable

Import Statement

Objective-C

@import UIKit;

Swift

import UIKit

Availability

Not Applicable

The UIKit framework defines a number of functions, many of them used in graphics and drawing operations.

Functions

Application Launch


    
      
           UIApplicationMain(_:_:_:_:)
      
      
           UIApplicationMain

This function is called in the main entry point to create the application object and the application delegate and set up the event cycle.

Declaration

Swift

func UIApplicationMain(_ argc: Int32, _ argv: UnsafeMutablePointer<UnsafeMutablePointer<Int8>>, _ principalClassName: String?, _ delegateClassName: String?) -> Int32

Objective-C

int UIApplicationMain ( int argc, char * _Nonnull argv[], NSString *principalClassName, NSString *delegateClassName );

Parameters

`argc`	The count of arguments in `argv`; this usually is the corresponding parameter to `main`.
`argv`	A variable list of arguments; this usually is the corresponding parameter to `main`.
`principalClassName`	The name of the `UIApplication` class or subclass. If you specify `nil`, `UIApplication` is assumed.
`delegateClassName`	The name of the class from which the application delegate is instantiated. If `principalClassName` designates a subclass of `UIApplication`, you may designate the subclass as the delegate; the subclass instance receives the application-delegate messages. Specify `nil` if you load the delegate object from your application’s main nib file.

Return Value

Even though an integer return type is specified, this function never returns. When users exits an iOS application by pressing the Home button, the application moves to the background.

Discussion

This function instantiates the application object from the principal class and instantiates the delegate (if any) from the given class and sets the delegate for the application. It also sets up the main event loop, including the application’s run loop, and begins processing events. If the application’s Info.plist file specifies a main nib file to be loaded, by including the NSMainNibFile key and a valid nib file name for the value, this function loads that nib file.

Despite the declared return type, this function never returns. For more information on how this function behaves, see “Core App Objects” in App Programming Guide for iOS.

Availability

Available in iOS 2.0 and later.

Image Manipulation


    
      
           UIImageJPEGRepresentation(_:_:)
      
      
           UIImageJPEGRepresentation

Returns the data for the specified image in JPEG format.

Declaration

Swift

func UIImageJPEGRepresentation(_ image: UIImage, _ compressionQuality: CGFloat) -> NSData?

Objective-C

NSData * UIImageJPEGRepresentation ( UIImage *image, CGFloat compressionQuality );

Parameters

`image`	The original image data.
`compressionQuality`	The quality of the resulting JPEG image, expressed as a value from 0.0 to 1.0. The value 0.0 represents the maximum compression (or lowest quality) while the value 1.0 represents the least compression (or best quality).

Return Value

A data object containing the JPEG data, or nil if there was a problem generating the data. This function may return nil if the image has no data or if the underlying CGImageRef contains data in an unsupported bitmap format.

Discussion

If the image object’s underlying image data has been purged, calling this function forces that data to be reloaded into memory.

Availability

Available in iOS 2.0 and later.

UIImagePNGRepresentation(_:) UIImagePNGRepresentation

Returns the data for the specified image in PNG format

Declaration

Swift

func UIImagePNGRepresentation(_ image: UIImage) -> NSData?

Objective-C

NSData * UIImagePNGRepresentation ( UIImage *image );

Parameters

image

The original image data.

Return Value

A data object containing the PNG data, or nil if there was a problem generating the data. This function may return nil if the image has no data or if the underlying CGImageRef contains data in an unsupported bitmap format.

Discussion

If the image object’s underlying image data has been purged, calling this function forces that data to be reloaded into memory.

Availability

Available in iOS 2.0 and later.

Image and Movie Saving


    
      
           UIImageWriteToSavedPhotosAlbum(_:_:_:_:)
      
      
           UIImageWriteToSavedPhotosAlbum

Adds the specified image to the user’s Camera Roll album.

Declaration

Swift

func UIImageWriteToSavedPhotosAlbum(_ image: UIImage, _ completionTarget: AnyObject?, _ completionSelector: Selector, _ contextInfo: UnsafeMutablePointer<Void>)

Objective-C

void UIImageWriteToSavedPhotosAlbum ( UIImage *image, id completionTarget, SEL completionSelector, void *contextInfo );

Parameters

`image`	The image to write to the Camera Roll album.
`completionTarget`	Optionally, the object whose selector should be called after the image has been written to the Camera Roll album.
`completionSelector`	The method selector, of the `completionTarget` object, to call. This optional method should conform to the following signature: `- (void) image: (UIImage ) image` `didFinishSavingWithError: (NSError ) error` `contextInfo: (void *) contextInfo;`
`contextInfo`	An optional pointer to any context-specific data that you want passed to the completion selector.

Discussion

When used with an image picker controller, you would typically call this function within your imagePickerController:didFinishPickingMediaWithInfo: delegate method implementation.

The use of the completionTarget, completionSelector, and contextInfo parameters is optional and necessary only if you want to be notified asynchronously when the function finishes writing the image to the user’s Camera Roll or Saved Photos album. If you do not want to be notified, pass nil for these parameters.

When used on an iOS device without a camera, this method adds the image to the Saved Photos album rather than to the Camera Roll album.

Availability

Available in iOS 2.0 and later.

Declaration

Swift

func UISaveVideoAtPathToSavedPhotosAlbum(_ videoPath: String, _ completionTarget: AnyObject?, _ completionSelector: Selector, _ contextInfo: UnsafeMutablePointer<Void>)

Objective-C

void UISaveVideoAtPathToSavedPhotosAlbum ( NSString *videoPath, id completionTarget, SEL completionSelector, void *contextInfo );

Parameters

`videoPath`	The filesystem path to the movie file you want to save to the Camera Roll album.
`completionTarget`	Optionally, the object whose selector should be called after the movie has been written to the Camera Roll album.
`completionSelector`	The method selector, of the `completionTarget` object, to call. This optional method should conform to the following signature: `- (void) video: (NSString ) videoPath` `didFinishSavingWithError: (NSError ) error` `contextInfo: (void *) contextInfo;`
`contextInfo`	An optional pointer to any context-specific data that you want passed to the completion selector.

Discussion

When used with an image picker controller, you would typically call this function within your imagePickerController:didFinishPickingMediaWithInfo: delegate method implementation.

Before calling this function, call the UIVideoAtPathIsCompatibleWithSavedPhotosAlbum function to determine if it is possible to save movies to the Camera Roll album. For a code example, refer to Camera Programming Topics for iOS.

The use of the completionTarget, completionSelector, and contextInfo parameters is optional and necessary only if you want to be notified asynchronously when the function finishes writing the movie to the user’s Camera Roll or Saved Photos album. If you do not want to be notified, pass nil for these parameters.

When used on an iOS device without a camera, this method adds the movie to the Saved Photos album rather than to the Camera Roll album.

Availability

Available in iOS 3.1 and later.

Graphics

UIGraphicsGetCurrentContext() UIGraphicsGetCurrentContext

Returns the current graphics context.

Declaration

Swift

func UIGraphicsGetCurrentContext() -> CGContext?

Objective-C

CGContextRef UIGraphicsGetCurrentContext ( void );

Return Value

The current graphics context.

Discussion

The current graphics context is nil by default. Prior to calling its drawRect: method, view objects push a valid context onto the stack, making it current. If you are not using a UIView object to do your drawing, however, you must push a valid context onto the stack manually using the UIGraphicsPushContext function.

This function may be called from any thread of your app.

Availability

Available in iOS 2.0 and later.

See Also

UIGraphicsPushContext
UIGraphicsPopContext
UIGraphicsPushContext(_:) UIGraphicsPushContext

Makes the specified graphics context the current context.

Declaration

Swift

func UIGraphicsPushContext(_ context: CGContext)

Objective-C

void UIGraphicsPushContext ( CGContextRef context );

Parameters

context

The graphics context to make the current context.

Discussion

You can use this function to save the previous graphics state and make the specified context the current context. You must balance calls to this function with matching calls to the UIGraphicsPopContext function.

This function may be called from any thread of your app.

Availability

Available in iOS 2.0 and later.

See Also

UIGraphicsPopContext
UIGraphicsPopContext() UIGraphicsPopContext

Removes the current graphics context from the top of the stack, restoring the previous context.

Declaration

Swift

func UIGraphicsPopContext()

Objective-C

void UIGraphicsPopContext ( void );

Discussion

Use this function to balance calls to the UIGraphicsPushContext function.

This function may be called from any thread of your app.

Availability

Available in iOS 2.0 and later.

See Also

UIGraphicsPushContext
UIGraphicsBeginImageContext(_:) UIGraphicsBeginImageContext

Creates a bitmap-based graphics context and makes it the current context.

Declaration

Swift

func UIGraphicsBeginImageContext(_ size: CGSize)

Objective-C

void UIGraphicsBeginImageContext ( CGSize size );

Parameters

size

The size of the new bitmap context. This represents the size of the image returned by the UIGraphicsGetImageFromCurrentImageContext function.

Discussion

This function is equivalent to calling the UIGraphicsBeginImageContextWithOptions function with the opaque parameter set to NOfalse and a scale factor of 1.0.

This function may be called from any thread of your app.

Availability

Available in iOS 2.0 and later.


    
      
           UIGraphicsBeginImageContextWithOptions(_:_:_:)
      
      
           UIGraphicsBeginImageContextWithOptions

Creates a bitmap-based graphics context with the specified options.

Declaration

Swift

func UIGraphicsBeginImageContextWithOptions(_ size: CGSize, _ opaque: Bool, _ scale: CGFloat)

Objective-C

void UIGraphicsBeginImageContextWithOptions ( CGSize size, BOOL opaque, CGFloat scale );

Parameters

`size`	The size (measured in points) of the new bitmap context. This represents the size of the image returned by the `UIGraphicsGetImageFromCurrentImageContext` function. To get the size of the bitmap in pixels, you must multiply the width and height values by the value in the `scale` parameter.
`opaque`	A Boolean flag indicating whether the bitmap is opaque. If you know the bitmap is fully opaque, specify `YEStrue` to ignore the alpha channel and optimize the bitmap’s storage. Specifying `NOfalse` means that the bitmap must include an alpha channel to handle any partially transparent pixels.
`scale`	The scale factor to apply to the bitmap. If you specify a value of `0.0`, the scale factor is set to the scale factor of the device’s main screen.

Discussion

You use this function to configure the drawing environment for rendering into a bitmap. The format for the bitmap is a ARGB 32-bit integer pixel format using host-byte order. If the opaque parameter is YEStrue, the alpha channel is ignored and the bitmap is treated as fully opaque (kCGImageAlphaNoneSkipFirst | kCGBitmapByteOrder32Host). Otherwise, each pixel uses a premultipled ARGB format (kCGImageAlphaPremultipliedFirst | kCGBitmapByteOrder32Host).

The environment also uses the default coordinate system for UIKit views, where the origin is in the upper-left corner and the positive axes extend down and to the right of the origin. The supplied scale factor is also applied to the coordinate system and resulting images. The drawing environment is pushed onto the graphics context stack immediately.

While the context created by this function is the current context, you can call the UIGraphicsGetImageFromCurrentImageContext function to retrieve an image object based on the current contents of the context. When you are done modifying the context, you must call the UIGraphicsEndImageContext function to clean up the bitmap drawing environment and remove the graphics context from the top of the context stack. You should not use the UIGraphicsPopContext function to remove this type of context from the stack.

In most other respects, the graphics context created by this function behaves like any other graphics context. You can change the context by pushing and popping other graphics contexts. You can also get the bitmap context using the UIGraphicsGetCurrentContext function.

This function may be called from any thread of your app.

Availability

Available in iOS 4.0 and later.

Declaration

Swift

func UIRectClip(_ rect: CGRect)

Objective-C

void UIRectClip ( CGRect rect );

Parameters


  rect

The rectangle to intersect with the clipping region. If the width or height of the rectangle are less than 0, this function does not change the clipping path.

Discussion

Each call to this function permanently shrinks the clipping path of the current graphics context using the specified rectangle. You cannot use this function to expand the clipping region path. If the current graphics context is nil, this function does nothing.

If you need to return the clipping path to its original shape in your drawing code, you should save the current graphics context before calling this function. To save the current state of the graphics context, call the CGContextSaveGState function before making your modifications. When you are ready to restore the original clipping region, you can then use the CGContextRestoreGState function to restore the previous graphics state.

This function may be called from any thread of your app.

Availability

Available in iOS 2.0 and later.

Creating a Dictionary

NSDictionaryOfVariableBindings
Creates a dictionary wherein the keys are string representations of the corresponding values’ variable names.

Declaration

Objective-C

#define NSDictionaryOfVariableBindings(...) _NSDictionaryOfVariableBindings(@"" # __VA_ARGS__, __VA_ARGS__, nil)
Discussion

This macro is particularly useful when creating Autolayout constraints—see Auto Layout Guide. For example, the following code:
NSDictionary *viewsDictionary = NSDictionaryOfVariableBindings(button1, button2);
creates the dictionary { @"button1" = button1, @"button2 = button2 }.
Availability

Available in iOS 6.0 and later.

PDF Creation


    
      
           UIGraphicsBeginPDFContextToData(_:_:_:)
      
      
           UIGraphicsBeginPDFContextToData

Creates a PDF-based graphics context that targets the specified mutable data object.

Declaration

Swift

func UIGraphicsBeginPDFContextToData(_ data: NSMutableData, _ bounds: CGRect, _ documentInfo: [NSObject : AnyObject]?)

Objective-C

void UIGraphicsBeginPDFContextToData ( NSMutableData *data, CGRect bounds, NSDictionary *documentInfo );

Parameters

`data`	The data object to receive the PDF output data.
`bounds`	A rectangle that specifies the default size and location of PDF pages. (This value is used as the default media box for each new page.) The origin of the rectangle should typically be (0, 0). Specifying an empty rectangle (`CGRectZero`) sets the default page size to 8.5 by 11 inches (612 by 792 points).
`documentInfo`	A dictionary that specifies additional information to be associated with the PDF file. You can use these keys to specify additional metadata and security information for the PDF, such as the author of the PDF or the password for accessing it. The keys in this dictionary are the same keys you pass to the `CGPDFContextCreate` function and are described in the Auxiliary Dictionary Keys section of CGPDFContext Reference. The dictionary is retained by the new context, so on return you may safely release it. Specify `nil` if you do not want to associate any additional information with the PDF document.

Discussion

After creating the graphics context, this function makes it the current drawing context. Any subsequent drawing commands are therefore captured and turned into PDF data. When you are done drawing, you must call the UIGraphicsEndPDFContext function to close the PDF graphics context.

You can use all of the same drawing routines that you would normally use to draw the contents of your application. The graphics context converts all drawing commands into PDF drawing commands automatically. However, before you issue any drawing commands to a PDF context, you must start a new page by calling the UIGraphicsBeginPDFPage or UIGraphicsBeginPDFPageWithInfo function. You can also use these functions to define additional pages later.

After creating it, you can get the PDF context using the UIGraphicsGetCurrentContext function.

Availability

Available in iOS 3.2 and later.

Declaration

Swift

func UIGraphicsBeginPDFContextToFile(_ path: String, _ bounds: CGRect, _ documentInfo: [NSObject : AnyObject]?) -> Bool

Objective-C

BOOL UIGraphicsBeginPDFContextToFile ( NSString *path, CGRect bounds, NSDictionary *documentInfo );

Parameters

`path`	A POSIX-style path string identifying the location of the resulting PDF file. The specified path may be relative or a full path name. If a file does not exist at the specified path, one is created; otherwise, the contents of any existing file are deleted. The directories in the path must exist.
`bounds`	A rectangle that specifies the default size and location of PDF pages. (This value is used as the default media box for each new page.) The origin of the rectangle should typically be (0, 0). Specifying an empty rectangle (`CGRectZero`) sets the default page size to 8.5 by 11 inches (612 by 792 points).
`documentInfo`	A dictionary that specifies additional information to be associated with the PDF file. You can use these keys to specify additional metadata and security information for the PDF, such as the author of the PDF or the password for accessing it. The keys in this dictionary are the same keys you pass to the `CGPDFContextCreate` function and are described in the Auxiliary Dictionary Keys section of CGPDFContext Reference. The dictionary is retained by the new context, so on return you may safely release it. Specify `nil` if you do not want to associate any additional information with the PDF document.

Return Value

YEStrue if the PDF context was created successfully or NOfalse if it was not.

Discussion

You can use all of the same drawing routines that you would normally use to draw the contents of your application. However, before you issue any drawing commands to a PDF context, you must start a new page by calling the UIGraphicsBeginPDFPage or UIGraphicsBeginPDFPageWithInfo function. You can also use these functions to define additional pages later.

After creating it, you can get the PDF context using the UIGraphicsGetCurrentContext function.

Availability

Available in iOS 3.2 and later.

UIGraphicsEndPDFContext() UIGraphicsEndPDFContext

Closes a PDF graphics context and pops it from the current context stack.

Declaration

Swift

func UIGraphicsEndPDFContext()

Objective-C

void UIGraphicsEndPDFContext ( void );

Discussion

You must call this function after you finish drawing to a PDF graphics context. This function closes the current open page and removes the PDF context from the graphics context stack. It also releases the CGContextRef associated with the PDF context. If the current graphics context is not a PDF context, this function does nothing.

Availability

Available in iOS 3.2 and later.
UIGraphicsBeginPDFPage() UIGraphicsBeginPDFPage

Marks the beginning of a new page in a PDF context and configures it using default values.

Declaration

Swift

func UIGraphicsBeginPDFPage()

Objective-C

void UIGraphicsBeginPDFPage ( void );

Discussion

This function ends any previous page before beginning a new one. It sets the media box of the new page to the rectangle you specified when you created the PDF context.

If the current graphics context is not a PDF context, this function does nothing.

You must call this function or the UIGraphicsBeginPDFPageWithInfo function before you issue any drawing commands.

Availability

Available in iOS 3.2 and later.


    
      
           UIGraphicsBeginPDFPageWithInfo(_:_:)
      
      
           UIGraphicsBeginPDFPageWithInfo

Marks the beginning of a new page in a PDF context and configures it using the specified values.

Declaration

Swift

func UIGraphicsBeginPDFPageWithInfo(_ bounds: CGRect, _ pageInfo: [NSObject : AnyObject]?)

Objective-C

void UIGraphicsBeginPDFPageWithInfo ( CGRect bounds, NSDictionary *pageInfo );

Parameters


  bounds

A rectangle that specifies the size and location of the new PDF page. This rectangle corresponds to the media box rectangle for the page.


  pageInfo

A dictionary that specifies additional page-related information, such as the boxes that define different parts of the page. For a list of keys you can include in this dictionary, see Box Dictionary Keys in CGPDFContext Reference. The dictionary is retained by the new page, so you may release it after this function returns.

Specify nil if you do not want to associate any additional information with the page.

Discussion

This function ends any previous page before beginning a new one. It sets the media box of the new page to the value in the kCGPDFContextMediaBox key of the pageInfo dictionary, or to the value in the bounds parameter if the dictionary does not contain the key.

If the current graphics context is not a PDF context, this function does nothing.

You must call this function or the UIGraphicsBeginPDFPageWithInfo function before you issue any drawing commands.

Availability

Available in iOS 3.2 and later.

UIGraphicsGetPDFContextBounds() UIGraphicsGetPDFContextBounds

Returns the current page bounds.

Declaration

Swift

func UIGraphicsGetPDFContextBounds() -> CGRect

Objective-C

CGRect UIGraphicsGetPDFContextBounds ( void );

Return Value

The current page bounds associated with the PDF context or CGRectZero if the current context is not a PDF context.

Discussion

If a page has not yet been started, this function returns the default media box you specified when you created the PDF context; otherwise, it returns the page bounds for the current page.

Availability

Available in iOS 3.2 and later.


    
      
           UIGraphicsAddPDFContextDestinationAtPoint(_:_:)
      
      
           UIGraphicsAddPDFContextDestinationAtPoint

Creates a jump destination in the current page.

Declaration

Swift

func UIGraphicsAddPDFContextDestinationAtPoint(_ name: String, _ point: CGPoint)

Objective-C

void UIGraphicsAddPDFContextDestinationAtPoint ( NSString *name, CGPoint point );

Parameters

`name`	The name of the destination point. The name you assign is local to the PDF document and is what you use when creating links to this destination.
`point`	A point on the current page of the PDF context.

Discussion

This function marks the specified point in the current page as the destination of a jump. When the user taps a link that takes them to this jump destination, the PDF document scrolls until the specified point is visible.

If the current graphics context is not a PDF context, this function does nothing.

For information on how to create links to this destination, see the UIGraphicsSetPDFContextDestinationForRect function.

Availability

Available in iOS 3.2 and later.


    
      
           UIGraphicsSetPDFContextDestinationForRect(_:_:)
      
      
           UIGraphicsSetPDFContextDestinationForRect

Links a rectangle on the current page to the specified jump destination.

Declaration

Swift

func UIGraphicsSetPDFContextDestinationForRect(_ name: String, _ rect: CGRect)

Objective-C

void UIGraphicsSetPDFContextDestinationForRect ( NSString *name, CGRect rect );

Parameters

`name`	A named destination in the PDF document. This is the same name you used when creating the jump destination using the `UIGraphicsAddPDFContextDestinationAtPoint` function.
`rect`	A rectangle on the current page of the PDF context.

Discussion

You use this function to create live links within a PDF document. Tapping the specified rectangle in the PDF document causes the document to display the contents at the associated jump destination.

If the current graphics context is not a PDF context, this function does nothing.

Availability

Available in iOS 3.2 and later.

UIGraphicsSetPDFContextURLForRect(_:_:) UIGraphicsSetPDFContextURLForRect

Links a rectangle on the current page to the specified URL.

Declaration

Swift

func UIGraphicsSetPDFContextURLForRect(_ url: NSURL, _ rect: CGRect)

Objective-C

void UIGraphicsSetPDFContextURLForRect ( NSURL *url, CGRect rect );

Parameters

url

The URL to open.

rect

A rectangle on the current page of the PDF context.

Discussion

You use this function to create external links within a PDF document. If the URL you specify is a type handled by a different application, tapping the rectangle opens that application.

If the current graphics context is not a PDF context, this function does nothing.

Availability

Available in iOS 3.2 and later.

String Conversions


    
      
           CGAffineTransformFromString(_:)
      
      
           CGAffineTransformFromString

Returns a Core Graphics affine transform structure corresponding to the data in a given string.

Declaration

Swift

func CGAffineTransformFromString(_ string: String) -> CGAffineTransform

Objective-C

CGAffineTransform CGAffineTransformFromString ( NSString *string );

Parameters


  string

A string whose contents are of the form “{a, b, c, d, tx, ty}”, where a, b, c, d, tx, and ty are the floating-point component values of the CGAffineTransform data structure. An example of a valid string is @”{1,0,0,1,2.5,3.0}”. The string is not localized, so items are always separated with a comma. For information about the position of each value in the transform array, see CGAffineTransform Reference.

Return Value

A Core Graphics affine transform structure. If the string is not well-formed, the function returns the identity transform.

Discussion

In general, you should use this function only to convert strings that were previously created using the NSStringFromCGAffineTransform function.

Availability

Available in iOS 2.0 and later.

Declaration

Swift

func CGPointFromString(_ string: String) -> CGPoint

Objective-C

CGPoint CGPointFromString ( NSString *string );

Parameters


  string

A string whose contents are of the form “{x,y}”, where x is the x coordinate and y is the y coordinate. The x and y values can represent integer or float values. An example of a valid string is @”{3.0,2.5}”. The string is not localized, so items are always separated with a comma.

Return Value

A Core Graphics structure that represents a point. If the string is not well-formed, the function returns CGPointZero.

Discussion

In general, you should use this function only to convert strings that were previously created using the NSStringFromCGPoint function.

Availability

Available in iOS 2.0 and later.

Declaration

Swift

func CGRectFromString(_ string: String) -> CGRect

Objective-C

CGRect CGRectFromString ( NSString *string );

Parameters


  string

A string whose contents are of the form “{{x,y},{w, h}}”, where x is the x coordinate, y is the y coordinate, w is the width, and h is the height. These components can represent integer or float values. An example of a valid string is @”{{3,2},{4,5}}”. The string is not localized, so items are always separated with a comma.

Return Value

A Core Graphics structure that represents a rectangle. If the string is not well-formed, the function returns CGRectZero.

Discussion

In general, you should use this function only to convert strings that were previously created using the NSStringFromCGRect function.

Availability

Available in iOS 2.0 and later.

Declaration

Swift

func CGSizeFromString(_ string: String) -> CGSize

Objective-C

CGSize CGSizeFromString ( NSString *string );

Parameters


  string

A string whose contents are of the form “{w, h}”, where w is the width and h is the height. The w and h values can be integer or float values. An example of a valid string is @”{3.0,2.5}”. The string is not localized, so items are always separated with a comma.

Return Value

A Core Graphics structure that represents a size. If the string is not well-formed, the function returns CGSizeZero.

Discussion

In general, you should use this function only to convert strings that were previously created using the NSStringFromCGSize function.

Availability

Available in iOS 2.0 and later.

Declaration

Swift

func CGVectorFromString(_ string: String) -> CGVector

Objective-C

CGVector CGVectorFromString ( NSString *string );

Parameters


  string

A string whose contents are of the form “{dx, dy}”, where dx is the x-coordinate of the vector and dy is the y-coordinate. The dx and dy values can be integer or float values. An example of a valid string is @”{3.0,2.5}”. The string is not localized, so items are always separated with a comma.

Return Value

A Core Graphics structure that represents a two-dimensional vector. If the string is not well-formed, the function returns a vector whose dx and dy values are 0.

Discussion

In general, you should use this function only to convert strings that were previously created using the NSStringFromCGVector function.

Availability

Available in iOS 8.0 and later.

Declaration

Swift

func UIEdgeInsetsFromString(_ string: String) -> UIEdgeInsets

Objective-C

UIEdgeInsets UIEdgeInsetsFromString ( NSString *string );

Parameters


  string

A string whose contents are of the form “{top, left, bottom, right}”, where top, left, bottom, right are the floating-point component values of the UIEdgeInsets structure. An example of a valid string is @”{3.0,8.0,3.0,5.0}”. The string is not localized, so items are always separated with a comma.

Return Value

An edge insets data structure. If the string is not well-formed, the function returns UIEdgeInsetsZero.

Discussion

In general, you should use this function only to convert strings that were previously created using the NSStringFromUIEdgeInsets function.

Availability

Available in iOS 2.0 and later.

Managing Edge Insets


    
      
           UIEdgeInsetsMake(_:_:_:_:)
      
      
           UIEdgeInsetsMake

Creates an edge inset for a button or view.

Declaration

Swift

func UIEdgeInsetsMake(_ top: CGFloat, _ left: CGFloat, _ bottom: CGFloat, _ right: CGFloat) -> UIEdgeInsets

Objective-C

UIEdgeInsets UIEdgeInsetsMake ( CGFloat top, CGFloat left, CGFloat bottom, CGFloat right );

Parameters

`top`	The inset at the top of an object.
`left`	The inset on the left of an object
`bottom`	The inset on the bottom of an object.
`right`	The inset on the right of an object.

Return Value

An inset for a button or view

Discussion

An inset is a margin around the drawing rectangle where each side (left, right, top, and bottom) can have a different value.

Availability

Available in iOS 2.0 and later.

Managing Offsets

UIOffsetMake(_:_:) UIOffsetMake

Returns an offset structure from the given components.

Declaration

Swift

func UIOffsetMake(_ horizontal: CGFloat, _ vertical: CGFloat) -> UIOffset

Objective-C

UIOffset UIOffsetMake ( CGFloat horizontal, CGFloat vertical );

Parameters

horizontal

The horizontal offset.

vertical

The vertical offset.

Return Value

An offset structure with offsets horizontal and vertical.

Availability

Available in iOS 5.0 and later.
UIOffsetEqualToOffset(_:_:) UIOffsetEqualToOffset

Returns a Boolean value that indicates whether two offsets are equal.

Declaration

Swift

func UIOffsetEqualToOffset(_ offset1: UIOffset, _ offset2: UIOffset) -> Bool

Objective-C

BOOL UIOffsetEqualToOffset ( UIOffset offset1, UIOffset offset2 );

Parameters

offset1

The offset to compare with offset2.

offset2

The offset to compare with offset1.

Return Value

YEStrue if offset1 and offset2 are equal, otherwise NOfalse.

Availability

Available in iOS 5.0 and later.

Managing Float Ranges


    
      
           UIFloatRangeMake(_:_:)
      
      
           UIFloatRangeMake

Returns a new float range structure from the given components.

Declaration

Swift

func UIFloatRangeMake(_ minimum: CGFloat, _ maximum: CGFloat) -> UIFloatRange

Objective-C

UIFloatRange UIFloatRangeMake ( CGFloat minimum, CGFloat maximum );

Parameters

`minimum`	The minimum range value, which is typically less than or equal to `0`.
`maximum`	The maximum range value, which is typically greater than or equal to `0`.

Discussion

Float ranges are used in UIAttachmentBehavior objects to define the maximum range of translation or rotation for animations.

Availability

Available in iOS 9.0 and later.

UIFloatRangeIsInfinite(_:) UIFloatRangeIsInfinite

Returns a Boolean indicating whether the specified float range is infinitely large.

Declaration

Swift

func UIFloatRangeIsInfinite(_ range: UIFloatRange) -> Bool

Objective-C

BOOL UIFloatRangeIsInfinite ( UIFloatRange range );

Parameters

range

The range value to check.

Availability

Available in iOS 9.0 and later.
UIFloatRangeIsEqualToRange(_:_:) UIFloatRangeIsEqualToRange

Returns a Boolean indicating whether two float ranges are equivalent.

Declaration

Swift

func UIFloatRangeIsEqualToRange(_ range: UIFloatRange, _ otherRange: UIFloatRange) -> Bool

Objective-C

BOOL UIFloatRangeIsEqualToRange ( UIFloatRange range, UIFloatRange otherRange );

Parameters

range

The first range to compare.

otherRange

The second range to compare.

Discussion

Two ranges are considered equal when their minimum values are the same and their maximum values are the same. In practice, the minimum and maximum values do not have to be exactly equal, but the difference between each pair of values must be less than FLT_EPSILON.

Availability

Available in iOS 9.0 and later.

Interface Orientation

UIInterfaceOrientationIsPortrait(_:) UIInterfaceOrientationIsPortrait

Returns a Boolean value indicating whether the user interface is currently presented in a portrait orientation.

Declaration

Swift

func UIInterfaceOrientationIsPortrait(_ orientation: UIInterfaceOrientation) -> Bool

Objective-C

BOOL UIInterfaceOrientationIsPortrait ( UIInterfaceOrientation orientation );

Parameters

orientation

Specify the orientation constant to check.

Return Value

Returns YEStrue if the interface orientation is portrait, otherwise returns NOfalse.

Discussion

The interface orientation can be different than the device orientation. You typically call this function in your view controller code to check the current orientation.

Availability

Available in iOS 8.3 and later.
UIInterfaceOrientationIsLandscape(_:) UIInterfaceOrientationIsLandscape

Returns a Boolean value indicating whether the user interface is currently presented in a landscape orientation.

Declaration

Swift

func UIInterfaceOrientationIsLandscape(_ orientation: UIInterfaceOrientation) -> Bool

Objective-C

BOOL UIInterfaceOrientationIsLandscape ( UIInterfaceOrientation orientation );

Parameters

orientation

Specify the orientation constant to check.

Return Value

Returns YEStrue if the interface orientation is landscape, otherwise returns NOfalse.

Discussion

The interface orientation can be different than the device orientation. You typically call this function in your view controller code to check the current orientation.

Availability

Available in iOS 8.3 and later.

Device Orientation

UIDeviceOrientationIsPortrait(_:) UIDeviceOrientationIsPortrait

Returns a Boolean value indicating whether the device is in a portrait orientation.

Declaration

Swift

func UIDeviceOrientationIsPortrait(_ orientation: UIDeviceOrientation) -> Bool

Objective-C

BOOL UIDeviceOrientationIsPortrait ( UIDeviceOrientation orientation );

Parameters

orientation

Specify the value of the orientation property of the UIDevice class.

Return Value

Returns YEStrue if the device orientation is portrait, otherwise returns NOfalse.

Availability

Available in iOS 8.3 and later.
UIDeviceOrientationIsLandscape(_:) UIDeviceOrientationIsLandscape

Returns a Boolean value indicating whether the device is in a landscape orientation.

Declaration

Swift

func UIDeviceOrientationIsLandscape(_ orientation: UIDeviceOrientation) -> Bool

Objective-C

BOOL UIDeviceOrientationIsLandscape ( UIDeviceOrientation orientation );

Parameters

orientation

Specify the value of the orientation property of the UIDevice class.

Return Value

Returns YEStrue if the device orientation is landscape, otherwise returns NOfalse.

Availability

Available in iOS 8.3 and later.

Interface Idiom

UI_USER_INTERFACE_IDIOM() UI_USER_INTERFACE_IDIOM

Returns the interface idiom supported by the current device (recommended for apps that run in versions of iOS earlier than 3.2).

Declaration

Swift

func UI_USER_INTERFACE_IDIOM() -> UIUserInterfaceIdiom

Objective-C

UIUserInterfaceIdiom UI_USER_INTERFACE_IDIOM ( void );

Return Value

UIUserInterfaceIdiomPhone if the device is an iPhone or iPod touch or UIUserInterfaceIdiomPad if the device is an iPad.

Discussion

If your app runs in iOS 3.2 and later, use userInterfaceIdiom instead.

Availability

Available in iOS 8.3 and later.

Accessibility


    
      
           UIAccessibilityPostNotification(_:_:)
      
      
           UIAccessibilityPostNotification

Posts a notification to assistive applications.

Declaration

Swift

func UIAccessibilityPostNotification(_ notification: UIAccessibilityNotifications, _ argument: AnyObject?)

Objective-C

void UIAccessibilityPostNotification ( UIAccessibilityNotifications notification, id argument );

Parameters

`notification`	The notification to post (see “Notifications” in UIAccessibility Protocol Reference for a list of notifications).
`argument`	The argument specified by the notification. Pass `nil` unless a notification specifies otherwise.

Discussion

Your application might need to post accessibility notifications if you have user interface components that change very frequently or that appear and disappear.

Availability

Available in iOS 3.0 and later.


    
      
           UIAccessibilityConvertFrameToScreenCoordinates(_:_:)
      
      
           UIAccessibilityConvertFrameToScreenCoordinates

Converts the specified rectangle from view coordinates to screen coordinates.

Declaration

Swift

func UIAccessibilityConvertFrameToScreenCoordinates(_ rect: CGRect, _ view: UIView) -> CGRect

Objective-C

CGRect UIAccessibilityConvertFrameToScreenCoordinates ( CGRect rect, UIView *view );

Parameters

`rect`	A rectangle specified in the coordinate system of the specified `view`.
`view`	The view that contains the specified rectangle. This parameter must not be `nil`.

Return Value

The rectangle in screen coordinates.

Discussion

Use this function to convert accessibility frame rectangles to screen coordinates.

Availability

Available in iOS 7.0 and later.


    
      
           UIAccessibilityConvertPathToScreenCoordinates(_:_:)
      
      
           UIAccessibilityConvertPathToScreenCoordinates

Converts the specified path object to screen coordinates and returns a new path object with the results.

Declaration

Swift

func UIAccessibilityConvertPathToScreenCoordinates(_ path: UIBezierPath, _ view: UIView) -> UIBezierPath

Objective-C

UIBezierPath * UIAccessibilityConvertPathToScreenCoordinates ( UIBezierPath *path, UIView *view );

Parameters

`path`	The path object that you want to convert. The coordinate values used to create this path object should be relative to the coordinate system of the specified `view`. This parameter must not be `nil`.
`view`	The view whose coordinate system was used to define the path. This parameter must not be `nil`.

Return Value

A new path object that has the same shape as path but whose points are specified in screen coordinates.

Discussion

This function adjusts the points of the path you provide to values that the accessibility system can use. You can use it to convert path objects in use by your app’s user interface before handing them to the accessibility system.

Availability

Available in iOS 7.0 and later.

UIAccessibilityRegisterGestureConflictWithZoom() UIAccessibilityRegisterGestureConflictWithZoom

Warns users that application-specific gestures conflict with the system-defined Zoom accessibility gestures.

Declaration

Swift

func UIAccessibilityRegisterGestureConflictWithZoom()

Objective-C

void UIAccessibilityRegisterGestureConflictWithZoom ( void );

Discussion

Use this function if your application uses multi-finger gestures that conflict with the gestures used by system Zoom (that is, three-finger gestures). When this is the case, the user is presented with the choice of turning off Zoom or continuing.

Availability

Available in iOS 5.0 and later.


    
      
           UIAccessibilityRequestGuidedAccessSession(_:_:)
      
      
           UIAccessibilityRequestGuidedAccessSession

Transitions the app to or from Single App mode asynchronously.

Declaration

Swift

func UIAccessibilityRequestGuidedAccessSession(_ enable: Bool, _ completionHandler: (Bool) -> Void)

Objective-C

void UIAccessibilityRequestGuidedAccessSession ( BOOL enable, void (^completionHandler)(BOOL didSucceed) );

Parameters


  enable

Specify YEStrue to put the device into Single App mode for this app or NOfalse to exit Single App mode.


  completionHandler

The block that notifies your app of the success or failure of the operation. This block takes the following parameter:


  didSucceed

If YEStrue, the app transitioned to or from Single App mode successfully. If NOfalse, the app or device is not eligible for Single App mode or there was some other error.

Discussion

You can use this method to lock your app into Single App mode and to release it from that mode later. For example, a test-taking app might enter this mode at the beginning of a test and exit it when the user completes the test. Entering Single App mode is supported only for devices that are supervised using Mobile Device Management (MDM), and the app itself must be enabled for this mode by MDM. You must balance each call to enter Single App mode with a call to exit that mode.

Because entering or exiting Single App mode might take some time, this method executes asynchronously and notifies you of the results using the completionHandler block.

Availability

Available in iOS 7.0 and later.

Declaration

Swift

func UIAccessibilityZoomFocusChanged(_ type: UIAccessibilityZoomType, _ frame: CGRect, _ view: UIView)

Objective-C

void UIAccessibilityZoomFocusChanged ( UIAccessibilityZoomType type, CGRect frame, UIView *view );

Parameters

`type`	A `Introduction` constant that identifies the type of Zoom.
`frame`	The frame that is currently zoomed, in screen coordinates.
`view`	The view that contains the zoomed frame.

Availability

Available in iOS 5.0 and later.

UIAccessibilityIsBoldTextEnabled() UIAccessibilityIsBoldTextEnabled

Returns a Boolean value indicating whether bold text is enabled.

Declaration

Swift

func UIAccessibilityIsBoldTextEnabled() -> Bool

Objective-C

BOOL UIAccessibilityIsBoldTextEnabled ( void );

Return Value

YEStrue if the user has enabled Bold Text in Settings; otherwise, NOfalse.

Availability

Available in iOS 8.0 and later.
UIAccessibilityIsClosedCaptioningEnabled() UIAccessibilityIsClosedCaptioningEnabled

Returns a Boolean value indicating whether closed captioning is enabled.

Declaration

Swift

func UIAccessibilityIsClosedCaptioningEnabled() -> Bool

Objective-C

BOOL UIAccessibilityIsClosedCaptioningEnabled ( void );

Return Value

YEStrue if the user has enabled closed captioning in Settings; otherwise, NOfalse.

Availability

Available in iOS 5.0 and later.
UIAccessibilityDarkerSystemColorsEnabled() UIAccessibilityDarkerSystemColorsEnabled

Returns a Boolean value indicating whether darken colors is enabled.

Declaration

Swift

func UIAccessibilityDarkerSystemColorsEnabled() -> Bool

Objective-C

BOOL UIAccessibilityDarkerSystemColorsEnabled ( void );

Return Value

YEStrue if the user has enabled Darken Colors in Settings; otherwise, NOfalse.

Availability

Available in iOS 8.0 and later.
UIAccessibilityIsGrayscaleEnabled() UIAccessibilityIsGrayscaleEnabled

Returns a Boolean value indicating whether grayscale is enabled.

Declaration

Swift

func UIAccessibilityIsGrayscaleEnabled() -> Bool

Objective-C

BOOL UIAccessibilityIsGrayscaleEnabled ( void );

Return Value

YEStrue if the user has enabled Grayscale in Settings; otherwise, NOfalse.

Availability

Available in iOS 8.0 and later.
UIAccessibilityIsGuidedAccessEnabled() UIAccessibilityIsGuidedAccessEnabled

Returns a Boolean value indicating whether Guided Access is enabled.

Declaration

Swift

func UIAccessibilityIsGuidedAccessEnabled() -> Bool

Objective-C

BOOL UIAccessibilityIsGuidedAccessEnabled ( void );

Return Value

YEStrue if the user has enabled Guided Access in Settings; otherwise, NOfalse.

Availability

Available in iOS 6.0 and later.
UIAccessibilityIsInvertColorsEnabled() UIAccessibilityIsInvertColorsEnabled

Returns a Boolean value indicating whether inverted colors is enabled.

Declaration

Swift

func UIAccessibilityIsInvertColorsEnabled() -> Bool

Objective-C

BOOL UIAccessibilityIsInvertColorsEnabled ( void );

Return Value

YEStrue if the user has enabled inverted colors in Settings; otherwise, NOfalse.

Availability

Available in iOS 6.0 and later.
UIAccessibilityIsMonoAudioEnabled() UIAccessibilityIsMonoAudioEnabled

Returns a Boolean value indicating whether system audio is set to mono.

Declaration

Swift

func UIAccessibilityIsMonoAudioEnabled() -> Bool

Objective-C

BOOL UIAccessibilityIsMonoAudioEnabled ( void );

Return Value

YEStrue if mono audio is currently enabled; otherwise, NOfalse.

Availability

Available in iOS 5.0 and later.
UIAccessibilityIsReduceMotionEnabled() UIAccessibilityIsReduceMotionEnabled

Returns a Boolean value indicating whether reduce motion is enabled.

Declaration

Swift

func UIAccessibilityIsReduceMotionEnabled() -> Bool

Objective-C

BOOL UIAccessibilityIsReduceMotionEnabled ( void );

Return Value

YEStrue if the user has enabled Reduce Motion in Settings; otherwise, NOfalse.

Availability

Available in iOS 8.0 and later.
UIAccessibilityIsReduceTransparencyEnabled() UIAccessibilityIsReduceTransparencyEnabled

Returns a Boolean value indicating whether reduce transparency is enabled.

Declaration

Swift

func UIAccessibilityIsReduceTransparencyEnabled() -> Bool

Objective-C

BOOL UIAccessibilityIsReduceTransparencyEnabled ( void );

Return Value

YEStrue if the user has enabled Reduce Transparency in Settings; otherwise, NOfalse.

Availability

Available in iOS 8.0 and later.
UIAccessibilityIsSpeakScreenEnabled() UIAccessibilityIsSpeakScreenEnabled

Returns a Boolean value indicating whether speaking the screen is enabled.

Declaration

Swift

func UIAccessibilityIsSpeakScreenEnabled() -> Bool

Objective-C

BOOL UIAccessibilityIsSpeakScreenEnabled ( void );

Return Value

YEStrue if the user has enabled Speak Screen in Settings; otherwise, NOfalse.

Availability

Available in iOS 8.0 and later.
UIAccessibilityIsSpeakSelectionEnabled() UIAccessibilityIsSpeakSelectionEnabled

Returns a Boolean value indicating whether speaking the selection is enabled.

Declaration

Swift

func UIAccessibilityIsSpeakSelectionEnabled() -> Bool

Objective-C

BOOL UIAccessibilityIsSpeakSelectionEnabled ( void );

Return Value

YEStrue if the user has enabled Speak Selection in Settings; otherwise, NOfalse.

Availability

Available in iOS 8.0 and later.
UIAccessibilityIsSwitchControlRunning() UIAccessibilityIsSwitchControlRunning

Returns a Boolean value indicating whether Switch Control is enabled.

Declaration

Swift

func UIAccessibilityIsSwitchControlRunning() -> Bool

Objective-C

BOOL UIAccessibilityIsSwitchControlRunning ( void );

Return Value

YEStrue if the user has enabled Switch Control in Settings; otherwise, NOfalse.

Availability

Available in iOS 8.0 and later.
UIAccessibilityIsVoiceOverRunning() UIAccessibilityIsVoiceOverRunning

Returns a Boolean value indicating whether VoiceOver is running.

Declaration

Swift

func UIAccessibilityIsVoiceOverRunning() -> Bool

Objective-C

BOOL UIAccessibilityIsVoiceOverRunning ( void );

Return Value

YEStrue if VoiceOver is currently running; otherwise, NOfalse.

Discussion

You can use this function to customize your application’s UI specifically for VoiceOver users. For example, you might want UI elements that usually disappear quickly to persist onscreen for VoiceOver users. Note that you can also listen for the UIAccessibilityVoiceOverStatusChanged notification to find out when VoiceOver starts and stops.

Availability

Available in iOS 4.0 and later.

Text Manipulations

NSTextAlignmentToCTTextAlignment(_:) NSTextAlignmentToCTTextAlignment

Converts a UIKit text alignment constant value to the matching constant value used by Core Text.

Declaration

Swift

func NSTextAlignmentToCTTextAlignment(_ nsTextAlignment: NSTextAlignment) -> CTTextAlignment

Objective-C

CTTextAlignment NSTextAlignmentToCTTextAlignment ( NSTextAlignment nsTextAlignment );

Parameters

nsTextAlignment

The UIKit text alignment constant you want to convert.

Return Value

The Core Text alignment that corresponds to the value specified in nsTextAlignment.

Discussion

Use this function when you need to map between the UIKit and Core Text constants for text alignment.

Availability

Available in iOS 6.0 and later.
NSTextAlignmentFromCTTextAlignment(_:) NSTextAlignmentFromCTTextAlignment

Converts a Core Text alignment constant value to the matching constant value used by UIKit.

Declaration

Swift

func NSTextAlignmentFromCTTextAlignment(_ ctTextAlignment: CTTextAlignment) -> NSTextAlignment

Objective-C

NSTextAlignment NSTextAlignmentFromCTTextAlignment ( CTTextAlignment ctTextAlignment );

Parameters

ctTextAlignment

The Core text alignment constant you want to convert.

Return Value

The UIKit text alignment that corresponds to the value specified in ctTextAlignment.

Discussion

Use this function when you need to map between the Core Text and UIKit constants for text alignment.

Availability

Available in iOS 6.0 and later.

Guided Access Restriction State

UIGuidedAccessRestrictionStateForIdentifier(_:) UIGuidedAccessRestrictionStateForIdentifier

Returns the restriction state for the specified guided access restriction.

Declaration

Swift

func UIGuidedAccessRestrictionStateForIdentifier(_ restrictionIdentifier: String) -> UIGuidedAccessRestrictionState

Objective-C

UIGuidedAccessRestrictionState UIGuidedAccessRestrictionStateForIdentifier ( NSString *restrictionIdentifier );

Parameters

restrictionIdentifier

The string that uniquely identifies the guided access restriction.

Return Value

The current state of the guided access restriction. The initial state of all restrictions is UIGuidedAccessRestrictionStateAllow.

Availability

Available in iOS 7.0 and later.

`rect`	The rectangle defining the area in which to draw.
`blendMode`	The blend mode to use during drawing.

`rect`	The rectangle defining the area in which to draw.
`blendMode`	The blend mode to use during drawing.

`insets1`	An edge inset to compare with `insets2`.
`insets2`	An edge inset to compare with `insets1`.

`rect`	The rectangle to be adjusted.
`insets`	The edge insets to be applied to the adjustment.

`url`	The URL to open.
`rect`	A rectangle on the current page of the PDF context.

`horizontal`	The horizontal offset.
`vertical`	The vertical offset.

`offset1`	The offset to compare with `offset2`.
`offset2`	The offset to compare with `offset1`.

`range`	The first range to compare.
`otherRange`	The second range to compare.

UIKit Function Reference

Functions

Application Launch

Declaration

Parameters

Return Value

Discussion

Availability

Image Manipulation

Declaration

Parameters

Return Value

Discussion

Availability

Declaration

Parameters

Return Value

Discussion

Availability

Image and Movie Saving

Declaration

Parameters

Discussion

Availability

See Also

Declaration

Parameters

Discussion

Availability

See Also

Declaration

Parameters

Return Value

Discussion

Availability

See Also

Graphics

Declaration

Return Value

Discussion

Availability

See Also

Declaration

Parameters

Discussion

Availability

See Also

Declaration

Discussion

Availability

See Also

Declaration

Parameters

Discussion

Availability

Declaration

Parameters

Discussion

Availability

See Also

Declaration

Return Value

Discussion

Availability

See Also

Declaration

Discussion

Availability

See Also

Declaration

Parameters

Discussion

Availability

See Also

Declaration

Parameters

Discussion

Availability

Declaration

Parameters