DragDrop9.swift

let items = coordinator.items
var dIndexPath = destinationIndexPath
if dIndexPath.row >= collectionView.numberOfItems(inSection: 0)
{
  dIndexPath.row = collectionView.numberOfItems(inSection: 0) - 1
}
var sourceIndexPaths = [IndexPath]()
var destinationIndexPaths = [IndexPath]()
for item in items
{
  if let sourceIndexPath = item.sourceIndexPath
  {
    sourceIndexPaths.append(sourceIndexPath)
    destinationIndexPaths.append(dIndexPath)
    self.items2.remove(at: sourceIndexPath.row)
    self.items2.insert(item.dragItem.localObject as! String, at: dIndexPath.row)
    dIndexPath = IndexPath(row: dIndexPath.row + 1, section: 0)
  }
}
collectionView.performBatchUpdates({
  if collectionView === self.collectionView2
  {
    collectionView.deleteItems(at: sourceIndexPaths)
    collectionView.insertItems(at: destinationIndexPaths)
  }
})