- (NSUInteger)application:(UIApplication *)application supportedInterfaceOrientationsForWindow:(UIWindow *)window
 {
   if (_allowRotation == 1) {
     return UIInterfaceOrientationMaskLandscapeRight;
   }
   else
   {
     return (UIInterfaceOrientationMaskPortrait);
   }
 }

(void)viewDidLoad 
{ 
[super viewDidLoad]; 
AppDelegate * appDelegate = (AppDelegate *)[UIApplication sharedApplication].delegate; 
appDelegate.allowRotation = 1; 
}

AppDelegate *delegate = [[UIApplication sharedApplication]delegate];
  delegate.allowRotation = 0;