title: View being blocked by UITransitionView after being presented
body: <p>I have a side navigation controller and present it via a UIButton. When I make this NC the root view controller directly by <code>[self presentviewcontroller: NC animated: YES completion: nil]</code>, some reason the menu side of the NC is blocked by a <code>UITransitionView</code> that I cannot get to disappear.</p>
  
  <p>I've attached an image of the <a href="https://i.stack.imgur.com/qnlng.png" rel="noreferrer"><img src="https://i.stack.imgur.com/qnlng.png" alt="view hierarchy"></a>. <a href="https://i.stack.imgur.com/07Muy.png" rel="noreferrer"><img src="https://i.stack.imgur.com/07Muy.png" alt="Here"></a> is another.</p>
  
  <p>I have tried the following:</p>
  
  <pre><code>UIWindow *window = [(AppDelegate *)[[UIApplication sharedApplication] delegate] window];
      window.backgroundColor = kmain;
  
  
      CATransition* transition = [CATransition animation];
      transition.duration = .5;
      transition.timingFunction = [CAMediaTimingFunction functionWithName:kCAMediaTimingFunctionEaseInEaseOut];
      transition.type = kCATransitionPush;
      transition.subtype = kCATransitionFromTop;
  
      [nc.view.layer addAnimation:transition forKey:kCATransition];
  
      [UIView transitionWithView:window
                        duration:0.5
                         options:UIViewAnimationOptionTransitionNone
                      animations:^{ window.rootViewController = nc; }
                      completion:^(BOOL finished) {
                          for (UIView *subview in window.subviews) {
                              if ([subview isKindOfClass:NSClassFromString(@"UITransitionView")]) {
                                  [subview removeFromSuperview];
                              }
                          }
                      }];
  </code></pre>
  
  <p>But it is very hacky, and as the rootviewcontroller of the window changes during the transition, it's a little choppy and part of the navigationcontroller and the top right corner turn black. It looks very bad.</p>