Device Orientation Notification

viewController.m

- (void) viewDidAppear:(BOOL)animated {
    [super viewDidAppear:animated];
    [[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(orientationChanged:) name:@"UIDeviceOrientationDidChangeNotification" object: nil];
}

-(void)viewDidDisappear:(BOOL)animated {
    [super viewDidDisappear:animated];
    [[NSNotificationCenter defaultCenter] removeObserver:self name:@"UIDeviceOrientationDidChangeNotification" object:nil];
}

#pragma mark Rotation Methods

- (void)orientationChanged:(NSNotification *)notification
{
    [self performSelector:@selector(showScreen) withObject:nil afterDelay:0];
}

-(void)showScreen {
    
    UIDeviceOrientation deviceOrientation = [[UIDevice currentDevice] orientation];
    if (deviceOrientation == UIDeviceOrientationLandscapeLeft || deviceOrientation == UIDeviceOrientationLandscapeRight) {
        NSLog(@"changed landscape");
    } else {
        NSLog(@"changed portrait");
    }
    
}