title: UICollectionView: Is there a way to reload only the supplementary views?
body: <p>I have an uicollectionview with <em>supplementaryView</em> for each section.
   In each <em>supplementaryView</em> I have some buttons. 
  In dataSource method <em>collectionView:viewForSupplementaryElementOfKind:atIndexPath:</em> I'm setting the buttons tags with the <em>indexPath.section</em>. I made some delegate methods when a button is pressed and send the section(button.tag) as parameter.</p>
  
  <p>Everything works fine, but here comes the problem:</p>
  
  <ul>
  <li>when I insert or delete a section it must update the buttons tags, but I don't want to reload all the items from each section.</li>
  </ul>
  
  <p>I've tried:</p>
  
  <ul>
  <li>to get the supplementaryViews with the dataSource method <em>collectionView:viewForSupplementaryElementOfKind:atIndexPath:</em> and call <em>layoutIfNeeded</em> method for each <em>supplementaryView</em>, in this way the <em>supplementaryViews</em> are reloading, but this approach multiply my <em>supplementaryViews</em>.</li>
  <li>a fast <em>for</em> in <em>collectionView.subviews</em> and get just the <em>supplementaryView</em> and call <em>layoutIfNeeded</em> method, but it doesn't reload, just the layout is reloading.</li>
  <li><em>reloadSections:</em> method, but this reload all items from the section  </li>
  </ul>
  
  <p>Ohh.. And I use <em>NSFetchedResultsController</em>(delegate) for inserting and deleting sections.</p>
  
  <p>Can anyone help me with this? Is there a way to reload only the <em>supplementaryView</em>? Is there other approach for this scenario?  </p>
  
  <p>Thank You!</p>