Class

ProcessInfo

A collection of information about the current process.

Overview

Each process has a single, shared ProcessInfo object, known as a process information agent.

The process information agent can return information such as arguments, environment variables, host name, and process name. The processInfo class method returns the shared agent for the current process—that is, the process whose object sent the message. For example, the following line returns the ProcessInfo object, which then provides the name of the current process:

let processName = NSProcessInfo.processInfo().processName

The ProcessInfo class also includes the operatingSystem() method, which returns an enum constant identifying the operating system on which the process is executing.

ProcessInfo objects attempt to interpret environment variables and command-line arguments in the user's default C string encoding if they cannot be converted to Unicode as UTF-8 strings. If neither the Unicode nor C string conversion works, these values are ignored by the ProcessInfo object.

Managing Activities

The system has heuristics to improve battery life, performance, and responsiveness of applications for the benefit of the user. You can use the following methods to manage activities that give hints to the system that your application has special requirements:

In response to creating an activity, the system will disable some or all of the heuristics so your application can finish quickly while still providing responsive behavior if the user needs it.

You use activities when your application is performing a long-running operation. If the activity can take different amounts of time (for example, calculating the next move in a chess game), it should use this API. This will ensure correct behavior when the amount of data or the capabilities of the user's computer varies. You should put your activity into one of two major categories:

  1. User initiated: These are finite length activities that the user has explicitly started. Examples include exporting or downloading a user specified file.

  2. Background: These are finite length activities that are part of the normal operation of your application but are not explicitly started by the user. Examples include autosaving, indexing, and automatic downloading of files.

In addition, if your application requires high priority I/O, you can include the latencyCritical flag (using a bitwise OR). You should only use this flag for activities like audio or video recording that really do require high priority.

If your activity takes place synchronously inside an event callback on the main thread, you do not need to use this API.

Be aware that failing to end these activities for an extended period of time can have significant negative impacts to the performance of your user's computer, so be sure to use only the minimum amount of time required. User preferences may override your application’s request.

You can also use this API to control automatic termination or sudden termination (see Sudden Termination). For example:

let activity = NSProcessInfo.processInfo().beginActivityWithOptions(.AutomaticTerminationDisabled, reason: "Good Reason")
// Perform some work
NSProcessInfo.processInfo().endActivity(activity)

is equivalent to:

NSProcessInfo.processInfo().disableAutomaticTermination("Good Reason")
// Perform some work
NSProcessInfo.processInfo().enableAutomaticTermination("Good Reason")

Because this API returns an object, it may be easier to pair begins and ends than when using the automatic termination API—if the object is deallocated before the endActivity(_:) call, the activity will be automatically ended.

This API also provides a mechanism to disable system-wide idle sleep and display idle sleep. These can have a large impact on the user experience, so be sure not to forget to end activities that disable sleep (including userInitiated).

Sudden Termination

macOS 10.6 and later includes a mechanism that allows the system to log out or shut down more quickly by, whenever possible, killing applications instead of requesting that they quit themselves.

Your application can enable this capability on a global basis and then manually override its availability during actions that could cause data corruption or a poor user experience by allowing sudden termination. Alternately, your application can just manually enable and disable this functionality.

The methods enableSuddenTermination() and disableSuddenTermination() decrement or increment, respectively, a counter whose value is 1 when the process is first created. When the counter's value is 0 the application is considered to be safely killable and may be killed by the system without any notification or event being sent to the process first.

Your application can support sudden termination upon launch by adding a key to the application’s Info.plist. If the NSSupportsSuddenTermination key exists in the Info.plist and has a value of true, it is the equivalent of calling enableSuddenTermination() during your application launch. This renders the application process killable right away. You can still override this behavior by invoking disableSuddenTermination().

Typically, you disable sudden termination whenever your application defers work that must be done before the application terminates. If, for example, your application defers writing data to disk, and sudden termination is enabled, you should bracket the sensitive operations with a call to disableSuddenTermination(), perform the necessary operations, and then send a balancing enableSuddenTermination() message.

In agents or daemon executables that don't depend on AppKit you can manually invoke enableSuddenTermination() right away. You can then use the enable and disable methods whenever the process has work it must do before it terminates.

Some AppKit functionality automatically disables sudden termination on a temporary basis to ensure data integrity.

  • UserDefaults temporarily disables sudden termination to prevent process killing between the time at which a default has been set and the time at which the preferences file including that default has been written to disk.

  • NSDocument temporarily disables sudden termination to prevent process killing between the time at which the user has made a change to a document and the time at which the user's change has been written to disk.

Thermal State and App Performance in macOS

In macOS, use the current thermal state to determine if your app should reduce system usage. In macOS 10.10.3 and later, you can register for the thermalStateDidChangeNotification to be notified when the thermal state changes. Use thermalState to query the current state. Your app should reduce system usage at higher thermal states. For recommended actions, see ProcessInfo.ThermalState.

Topics

Getting the Process Information Agent

class var processInfo: ProcessInfo

Returns the process information agent for the process.

Accessing Process Information

var arguments: [String]

Array of strings with the command-line arguments for the process.

var environment: [String : String]

The variable names (keys) and their values in the environment from which the process was launched.

var globallyUniqueString: String

Global unique identifier for the process.

var processIdentifier: Int32

The identifier of the process (often called process ID).

var processName: String

The name of the process.

Accessing User Information

Each user account in macOS has a full name (e.g., “Johnny Appleseed”) and an account name (e.g., “jappleseed”). You can view these names from the Users & Groups pane of System Preferences, and you can use either name to log in to your Mac.

var userName: String

Returns the account name of the current user.

var fullUserName: String

Returns the full name of the current user.

Sudden Application Termination

func disableSuddenTermination()

Disables the application for quickly killing using sudden termination.

func enableSuddenTermination()

Enables the application for quick killing using sudden termination.

Controlling Automatic Termination

func disableAutomaticTermination(String)

Disables automatic termination for the application.

func enableAutomaticTermination(String)

Enables automatic termination for the application.

var automaticTerminationSupportEnabled: Bool

A Boolean value indicating whether the app supports automatic termination.

Getting Host Information

var hostName: String

The name of the host computer on which the process is executing.

func operatingSystem()

Returns a constant to indicate the operating system on which the process is executing.

Deprecated
func operatingSystemName()

Returns a string containing the name of the operating system on which the process is executing.

Deprecated
var operatingSystemVersionString: String

A string containing the version of the operating system on which the process is executing.

var operatingSystemVersion: OperatingSystemVersion

The version of the operating system on which the process is executing.

func isOperatingSystemAtLeast(OperatingSystemVersion)

Returns a Boolean value indicating whether the version of the operating system on which the process is executing is the same or later than the given version.

Getting Computer Information

var processorCount: Int

The number of processing cores available on the computer.

var activeProcessorCount: Int

The number of active processing cores available on the computer.

var physicalMemory: UInt64

The amount of physical memory on the computer in bytes.

var systemUptime: TimeInterval

The amount of time the system has been awake since the last time it was restarted.

Managing Activities

func beginActivity(options: ProcessInfo.ActivityOptions = [], reason: String)

Begin an activity using the given options and reason.

func endActivity(NSObjectProtocol)

Ends the given activity.

func performActivity(options: ProcessInfo.ActivityOptions = [], reason: String, using: () -> Void)

Synchronously perform an activity defined by a given block using the given options.

func performExpiringActivity(withReason: String, using: (Bool) -> Void)

Performs the specified block asynchronously and notifies you if the process is about to be suspended.

Getting the Thermal State

var thermalState: ProcessInfo.ThermalState

The current thermal state of the system.

Determining Whether Low Power Mode is Enabled

var isLowPowerModeEnabled: Bool

A Boolean indicating whether Low Power Mode is enabled on an iOS device.

Constants

enum ProcessInfo.ThermalState

The following constants are provided by the NSProcessInfo class as return values for thermalState.

Anonymous

The following constants are provided by the NSProcessInfo class as return values for operatingSystem().

Notifications

class let thermalStateDidChangeNotification: NSNotification.Name

Posted when the thermal state of the system changes.

static let NSProcessInfoPowerStateDidChange: NSNotification.Name

Posted when the power state (Low Power Mode is enabled or disabled) of an iOS device changes.

Relationships

Inherits From

Conforms To

See Also

System Interaction

class NSBackgroundActivityScheduler

A task scheduler suitable for low priority operations that can run in the background.