1 - (id)initWithNibName:(NSString *)nibNameOrNil bundle:(NSBundle *)nibBundleOrNil
 2 {
 3     self = [super initWithNibName:nibNameOrNil bundle:nibBundleOrNil];
 4     if (self) {
 5         [[UIDevice currentDevice] beginGeneratingDeviceOrientationNotifications];
 6         [[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(orientationChanged:)
 7                                                      name:UIDeviceOrientationDidChangeNotification
 8                                                    object:[UIDevice currentDevice]];
 9     }
10     return self;
11 }

 1 - (void)orientationChanged:(NSNotification *)notification{
 2     UIDevice * device = notification.object;
 3     switch(device.orientation)
 4     {
 5         case UIDeviceOrientationPortrait:
 6             /* start special animation */
 7             break;
 8             
 9         case UIDeviceOrientationPortraitUpsideDown:
10             /* start special animation */
11             break;
12             
13         default:
14             break;
15     };
16 }