title: Transition between view controllers and rotation in iOS
body: <p>Consider a container view controller with two child view controllers (A and B), both added with <code>addChildViewController:</code>. Then:</p>
  
  <ol>
  <li><code>A.view</code> is added to the container view</li>
  <li>B is displayed by doing <code>transitionFromViewController</code> from A to B. B receives <code>viewWillLayoutSubviews</code> and all is good with the world.</li>
  <li>The device rotates while displaying B. Only B receives the rotation calls (<code>willRotateToInterfaceOrientation:</code> et all).</li>
  <li>A is displayed by doing <code>transitionFromViewController</code> from B to A. A doesn't receive <code>viewWillLayoutSubviews</code> and thus the layout is broken.</li>
  </ol>
  
  <p>Is this the expected behavior? If not, what might I be doing wrong? If yes, what should I do to notify A of the rotation change while displaying B?</p>