let mainStoryboard: UIStoryboard = UIStoryboard(name: "Main", bundle: nil)
let viewController = mainStoryboard.instantiateViewControllerWithIdentifier("LandingViewController")


UIView.transitionWithView( UIApplication.sharedApplication().keyWindow!,
                           duration: 0.5,
                           options: UIViewAnimationOptions.TransitionFlipFromLeft,
                           animations: { UIApplication.sharedApplication().keyWindow?.rootViewController = viewController; },
                           completion: nil)