title: UICollectionView with Search Header and Pull To Refresh
body: <p>The idea is to have a search view into a UICollectionView and still be able to use pull to refresh with UIRefreshControl. 
  The search and the UIRefreshControl will not be visible until the user scroll down the UICollectionView. </p>
  
  <pre><code>------------------
  | Pull To Refresh |
  ------------------
  |      Search     |
  ------------------    &lt;--- Above of this line the content is hidden
  |    A   |   B    |
  ------------------
  |    C   |   D    |
  ------------------
  |     Footer      |
  ------------------
  </code></pre>
  
  <p>I have tried implement the SearchView into an section header of the UICollectionView, but in this way I can not use reloadData while a cell of the collection view is the first responder. </p>
  
  <p>A good solution should make possible to: </p>
  
  <ul>
  <li>Update the CollectionView datasource while the user type into the search box</li>
  <li>Don't mess the animation of the UIRefreshControl</li>
  </ul>