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; Now I want to know is there any functions like these to know the changement of orientation in the file AppDelegate.m

- (void)navigationController:(UINavigationController *)navigationController
      willShowViewController:(UIViewController *)viewController
                    animated:(BOOL)animated {

    UINavigationBar *morenavbar = navigationController.navigationBar;
    UINavigationItem *morenavitem = morenavbar.topItem;
    //We don't need Edit button in More screen.
    morenavitem.rightBarButtonItem = nil;
    morenavitem.title = nil;
    UIImage *backgroundImage = [UIImage imageNamed:@"nav.png"];

    [morenavbar setBackgroundImage:backgroundImage 
         forBarMetrics:UIBarMetricsDefault];

    UIDeviceOrientation currentDeviceOrientation = 
           [[UIDevice currentDevice] orientation];
    UIInterfaceOrientation currentInterfaceOrientation = 
           [[UIApplication sharedApplication] statusBarOrientation];
    if (UIDeviceOrientationIsLandscape(currentDeviceOrientation)||
        UIDeviceOrientationIsLandscape(currentInterfaceOrientation)){
        UIImage *backgroundImageLandscape = [UIImage imageNamed:@"navbar_landscape.png"];
        [morenavbar setBackgroundImage:backgroundImageLandscape forBarMetrics:UIBarMetricsDefault];
    }

}

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