Instance Method


Asks the delegate whether the app’s state should be preserved.


optional func application(_ application: UIApplication, shouldSaveApplicationState coder: NSCoder) -> Bool



Your singleton app object.


The keyed archiver into which you can put high-level state information.

Return Value

true if the app’s state should be preserved or false if it should not.


Apps must implement this method and the application(_:shouldRestoreApplicationState:) method for state preservation to occur. In addition, your implementation of this method must return true each time UIKit tries to preserve the state of your app. You can return false to disable state preservation temporarily. For example, during testing, you could disable state preservation to test specific code paths.

You can add version information or any other contextual data to the provided coder object as needed. During restoration, you can use that information to help decide whether or not to proceed with restoring your app to its previous state.

See Also

Managing App State Restoration

func application(UIApplication, shouldRestoreApplicationState: NSCoder)

Asks the delegate whether the app’s saved state information should be restored.

func application(UIApplication, willEncodeRestorableStateWith: NSCoder)

Tells your delegate to save any high-level state information at the beginning of the state preservation process.

func application(UIApplication, didDecodeRestorableStateWith: NSCoder)

Tells your delegate to restore any high-level state information as part of the state restoration process.