title: Select and deselect UICollectionview to enable button
body: <p>I have collection view. This collectionview is multi selected when selected one item enable a button to send request, this part is working perfectly but when deselect one item disable button. I want when deselect all of item in collection view disable button.
  this is my code:
  this function for selected item :</p>
  
  <pre><code>func collectionView(_ collectionView: UICollectionView, didSelectItemAt indexPath: IndexPath) {
      let selectedCell = requestCollectionView.cellForItem(at: indexPath) as! RequestCollectionViewCell
  
      selectedCell.imageCell.image = (imageNotDimmed[indexPath.row])
  
      if selectedCell.isSelected == true{
          btnRequestInRequest.isEnabled = true
          btnRequestInRequest.setImage(#imageLiteral(resourceName: "SOS_Sending_Btn"), for: .normal)
          imageRingRequest.image = UIImage(named: "TheRing.png")
    }
      else if selectedCell.isHighlighted == false{
          btnRequestInRequest.setImage(#imageLiteral(resourceName: "TheRing_Dimmed"), for: .normal)
          imageRingRequest.image = UIImage(named: "SOS_Dimmed_Btn.png")
      }
  
  }
  </code></pre>
  
  <p>and this function fo deselect :</p>
  
  <pre><code>    func collectionView(_ collectionView: UICollectionView, didDeselectItemAt indexPath: IndexPath) {
      let deselected = requestCollectionView.cellForItem(at: indexPath) as! RequestCollectionViewCell
  
      deselected.imageCell.image = (imageDimmed[indexPath.row])
  
  }
  </code></pre>
  
  <p>I want when all of item in collection deselect button disable</p>