title: setRootViewController animation issue
body: <p>I have this code that I took from <a href="https://stackoverflow.com/a/26681430/1138498">here</a>:</p>
  
  <pre><code>func changeRootViewController(viewController: UIViewController) {
  
      if self.window?.rootViewController == nil {
          self.window?.rootViewController = viewController
          return
      }
  
      let snapShot = self.window?.snapshotViewAfterScreenUpdates(true)
      viewController.view.addSubview(snapShot!)
      self.window?.rootViewController = viewController
  
      UIView.animateWithDuration(0.5, animations: { () -&gt; Void in
  
          snapShot?.layer.opacity = 0.0
          snapShot?.layer.transform = CATransform3DMakeScale(1.5, 1.5, 1.5)
  
          }) { (value: Bool) -&gt; Void in
  
          snapShot?.removeFromSuperview()
      }
  }
  </code></pre>
  
  <p>It works fine, but it only have one problem, when the animation is finished the UIActivityIndicatorView frame is changing or there is a some kind of 'kick' to the view.</p>
  
  <p>You can see it in <a href="https://youtu.be/4KR2ih8zytw" rel="nofollow noreferrer">THIS</a> video.</p>
  
  <p>Thanks in advance.</p>