title: Using a custom transition layout when doing layout-to-layout navigation transitions
body: <p>I am setting my <code>UICollectionViewController</code>'s <code>useLayoutToLayoutNavigationTransitions</code> property to 'YES' in order to perform layout to layout transitions for <code>-[UINavigationController pushViewController:animated:]</code> and <code>popViewControllerAnimated:</code>. In addition, I have implemented pinch gesture-based interactive transitions.</p>
  
  <p>Also, I have defined a custom <code>UICollectionViewTransitionLayout</code> that behaves differently from the original behavior of <code>UICollectionViewTransitionLayout</code>. I create an instance of my "CustomLayoutTransition" object and return it from <code>-[UICollectionViewDelegate collectionView:transitionLayoutForOldLayout:newLayout:]</code>.</p>
  
  <p>I am expecting two behaviors when I do this</p>
  
  <p><em><code>CustomLayoutTransition</code> is used to perform custom layout-to-layout transitions</em><br>
  1) when interactive transition is triggered by pinch gesture, or<br>
  2) when I push/pop an instance of <code>UICollectionViewController</code>, e.g., by calling <code>[UINavigationController pushViewController:animated:]</code></p>
  
  <p>My expectation #1 seems to be correct, but #2 isn't; It seems that when I do push/pop programmatically, the original, Apple-provided <code>UICollectionViewTransitionLayout</code> is used instead of  my custom transition layout.</p>
  
  <p>Is it normal that <code>UICollectionViewTransitionLayout</code> is used instead of my custom transition layout in this circumstance?</p>
  
  <p>If this is normal behavior, is there a way to use the custom transition to perform layout-to-layout transitions when programmatically pushing/popping <code>UICollectionViewController</code>?</p>