Instance Method

applicationWillEnterForeground(_:)

Tells the delegate that the app is about to enter the foreground.

Declaration

optional func applicationWillEnterForeground(_ application: UIApplication)

Parameters

application

Your singleton app object.

Discussion

In iOS 4.0 and later, this method is called as part of the transition from the background to the active state. You can use this method to undo many of the changes you made to your app upon entering the background. The call to this method is invariably followed by a call to the applicationDidBecomeActive(_:) method, which then moves the app from the inactive to the active state.

The app also posts a willEnterForegroundNotification notification shortly before calling this method to give interested objects a chance to respond to the transition.

See Also

Responding to App Life-Cycle Events

func applicationDidBecomeActive(UIApplication)

Tells the delegate that the app has become active.

func applicationWillResignActive(UIApplication)

Tells the delegate that the app is about to become inactive.

func applicationDidEnterBackground(UIApplication)

Tells the delegate that the app is now in the background.

func applicationWillTerminate(UIApplication)

Tells the delegate when the app is about to terminate.

class let didEnterBackgroundNotification: NSNotification.Name

Posted when the app enters the background.

class let willEnterForegroundNotification: NSNotification.Name

Posted shortly before an app leaves the background state on its way to becoming the active app.

class let willResignActiveNotification: NSNotification.Name

Posted when the app is no longer active and loses focus.

class let willTerminateNotification: NSNotification.Name

Posted when the app is about to terminate.