Instance Method


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


- (void)applicationDidReceiveMemoryWarning:(UIApplication *)application;



Your singleton app object.


Your implementation of this method should free up as much memory as possible by purging cached data objects that can be recreated (or reloaded from disk) later. You use this method in conjunction with the didReceiveMemoryWarning of the UIViewController class and the UIApplicationDidReceiveMemoryWarningNotification notification to release memory throughout your app.

It is strongly recommended that you implement this method. If your app does not release enough memory during low-memory conditions, the system may terminate it outright.

See Also

Responding to Environment Changes

- applicationProtectedDataDidBecomeAvailable:

Tells the delegate that protected files are available now.

- applicationProtectedDataWillBecomeUnavailable:

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

- applicationSignificantTimeChange:

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


Posted when the protected files become available for your code to access.


Posted shortly before protected files are locked down and become inaccessible.


Posted when the app receives a warning from the operating system about low memory availability.


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.