Instance Method


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


optional func applicationWillEnterForeground(_ application: UIApplication)



Your singleton app object.


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 State Changes and System 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.

func applicationProtectedDataWillBecomeUnavailable(UIApplication)

Tells the delegate that the protected files are about to become unavailable.

func applicationProtectedDataDidBecomeAvailable(UIApplication)

Tells the delegate that protected files are available now.

func applicationDidReceiveMemoryWarning(UIApplication)

Tells the delegate when the app receives a memory warning from the system.

func applicationSignificantTimeChange(UIApplication)

Tells the delegate when there is a significant change in the time.