title: How to cancel a drag for UICollectionView?
body: <p>I try to drag from one collection view to another, it works fine, except that when I long-press an item and stop there. the item becomes the drag preview version of it and won't fall back to the normal state. How can I stop the active drag? </p>
  
  <p><strong>only the method is called:</strong> </p>
  
  <pre><code>(NSArray&lt;UIDragItem *&gt; *)collectionView:(UICollectionView *)collectionView itemsForBeginningDragSession:(id&lt;UIDragSession&gt;)session atIndexPath:(NSIndexPath *)indexPath
  </code></pre>
  
  <p>no drop delegate methods are called. drag end method isn't called either</p>