title: UICollectionView: Adding single Tap Gesture Recognizer to supplementary view
body: <p>I have a UICollectionView with a supplementary view -- in essence a header for the collection. Whenever I add a gesture recognizer to a UILabel within the headerView.xib using the interface builder, the app crashes giving me</p>
  
  <pre><code>*** Terminating app due to uncaught exception 'NSInternalInconsistencyException', reason: 'invalid nib registered for identifier (MY_HEADER) - nib must contain exactly one top level object which must be a UICollectionReusableView instance'
  </code></pre>
  
  <p>What is preventing me from adding a gesture recognizer to a UILabel within a supplementary view of a UICollectionView?</p>