title: How to disable UICollectionViewCell's user interaction while UIImageView.image still empty
body: <p>Is it possible to set <code>UICollectionViewCell</code>'s <code>userInteractionEnabled</code> to <code>false</code> while <code>imageView</code> still empty or don't let tp <code>performsegue</code> to the detail view? I'm trying to do it, but doesn't work. The example method below: </p>
  
  <pre><code> func collectionView(collectionView: UICollectionView, cellForItemAtIndexPath indexPath: NSIndexPath) -&gt; UICollectionViewCell {
  
      let cell = collectionView.dequeueReusableCellWithReuseIdentifier("Cell", forIndexPath: indexPath) as! CustomCollectionViewCell
              dispatch_sync(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0)) {
  
  
                  cell.userInteractionEnabled = false
                  cell.products.image = UIImage(named: "placeholderImage")
                  cell.activityIndicator.startAnimating()
                  let p = self.products[indexPath.row] as Product
  
                  if let img = UIImage(data: p.productImage) {
                      cell.products.image = img
                  }
                  else {
  
                      self.loadImages(p, indexPath: indexPath)
                  }
  
                  dispatch_async(dispatch_get_main_queue()) {
                      // update some UI
  
                      cell.activityIndicator.stopAnimating()
                      cell.userInteractionEnabled = true
  
                  }
  
              }
  
  
  
      return cell
  }
  </code></pre>