How can I know the orientation changed in AppDelegate

Question

The function of how the device know the changement of orientation is -(void)viewWillLayoutSubviews and -(void)viewDidLayoutSubviews But, they are just in the controllers;

Answer 1

You can register for notifications when rotation occurs

[[NSNotificationCenter defaultCenter] addObserver:self
                                         selector:@selector(handleDidChangeStatusBarOrientationNotification:) 
                                             name:UIApplicationDidChangeStatusBarOrientationNotification 
                                           object:nil];

Then implement the method that gets called when the message is sent

- (void)handleDidChangeStatusBarOrientationNotification:(NSNotification *)notification;
{
  // Do something interesting
  NSLog(@"The orientation is %@", [notification.userInfo objectForKey: UIApplicationStatusBarOrientationUserInfoKey]);
}

Alternatively check out the docs for UIApplicationDidChangeStatusBarOrientationNotification which will provide you with the