title: How to add header and footer view of UICollectionView in Swift
body: <p>I have added the delegate function in the controller class but it won't called at the run time. </p>
  
  <pre><code>func collectionView(collectionView: UICollectionView, viewForSupplementaryElementOfKind kind: String, atIndexPath indexPath: NSIndexPath) -&gt; UICollectionReusableView {
  }
  </code></pre>