View Controller method for lock button pressed?

Question

Is there an available view controller method that is called when the user presses the lock button? I'm looking for something like viewDidDisappear: or viewWillDisappear:, but specific to the case of the lock button being pressed.

Answer 1

A notification called UIApplicationDidEnterBackgroundNotification is posted when the user locks their phone. Here's how to listen for it:

In viewDidLoad: of your ViewController:

[[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(screenLocked) name:UIApplicationDidEnterBackgroundNotification object:nil];

Then, define a method (mine was called screenLocked above) and write code you want to be executed when the screen is locked.

-(void)screenLocked{
    //do stuff
}

Also, to do some necessary cleanup, add this method to your ViewController too.

-(void)dealloc{
    [[NSNotificationCenter defaultCenter] removeObserver:self name:UIApplicationDidEnterBackgroundNotification object:nil];
}

Answer 2

Try this :

- (void)applicationDidEnterBackground:(UIApplication *)application
{
  UIApplicationState state = [application applicationState];
  if (state == UIApplicationStateInactive) {
      NSLog(@"Sent to background by locking screen");
  } else if (state == UIApplicationStateBackground) {
      NSLog(@"Sent to background by home button/switching to other app");
  } 
}