title: UIModalPresentationCustom seems to stop modal from auto rotating
body: <p>So I have a viewcontroller who on a button click presents a modal. So The view controller that is presenting the modal only allows portrait animation. While the modal should allow all the rotation types. So if I present the modal with default animation the rotation works as expected e.g the view controller that is presenting the modal stays in portrait and the modal can rotate freely. So I wanted to use a custom transition to present and dismiss the modal controller. This is snippet which is used to present the modal.</p>
  
  <pre><code>SecondViewcontroller *sec = [[SecondViewcontroller alloc] initWithNibName:nil bundle:nil];
  sec.transitioningDelegate = self;
  sec.modalPresentationStyle = UIModalPresentationCustom;
  [self presentViewController:sec animated:YES completion:nil];
  </code></pre>
  
  <p>So I set up the UIViewControllerTransitioningDelegate methods for presenting and dismissing modals to return my Animator object. So now when I present the modal it now does this custom animation and everything appears to work. Except now the modal can no longer rotate and is stuck in portrait. So I decided to try and see if it was something odd with the animator causing it. So in the UIViewControllerTransitioningDelegate methods that return the custom Animator object I set them to return nil e.g use the default system animation. But no luck, it seems once I set</p>
  
  <pre><code>sec.modalPresentationStyle = UIModalPresentationCustom;
  </code></pre>
  
  <p>autorotation no longer works.</p>