func exitApplication() {     let app = UIApplication.sharedApplication().delegate as! AppDelegate    let window = app.window    dispatch_async(dispatch_get_main_queue(), {       UIView.animateWithDuration(0.5, animations: {         window!.alpha = 0        window?.frame = CGRectMake((window?.bounds.size.width)!/2.0, (window?.bounds.size.height)!/2.0, 0, 0)       }) { (finish) in        exit(0)       }     })   }