title: UICollectionView shouldShowMenuForItemAt Not Called
body: <p>I have a stock standard <code>UICollectionView</code> in a <code>UIViewController</code> that is its delegate. However the <code>shouldShowMenuForItemAt</code> func is not called for a long press. I have added a <code>didSelectItemAt</code> func which does get called on clicking a cell to make sure the delegate is indeed wired up correctly. </p>
  
  <p>I also implemented the <code>canPerformAction</code> to return true and <code>performAction</code> in the delegate along with the <code>canPerformAction</code> and <code>canBecomeFirstResponder</code> to return true in my <code>UICollectionViewCell</code> subclass. None of these func's get called for a long press of a cell. Any suggestions?</p>