Is there a method to check the UICollectionView item drag cancellation if the item wasn't moved?

问题

I use drag and drop to rearrange a collectionView. When I start the drag, I change the collectionView visualization. To change it back I need a method which will be executed in any case. Now if I start the drag and release the touch immediately, none of the following methods are executed:

not this:
    func collectionView(_ collectionView: UICollectionView,  dragSessionDidEnd session: UIDragSession)

not this:
    func collectionView(_ collectionView: UICollectionView, dropSessionDidEnd session: UIDropSession)

not this:
    func collectionView(_ collectionView: UICollectionView, performDropWith coordinator: UICollectionViewDropCoordinator)

Thank you.

回答1:

If you use the standard UICollectionViewDragDelegate implementation, you can react to the cell state change using the func dragStateDidChange(_ dragState: UICollectionViewCellDragState) of the cell class itself like:

override func dragStateDidChange(_ dragState: UICollectionViewCellDragState) {

    switch dragState {

    case .none:
        //
    case .lifting:
        //
    case .dragging:
        //
    }
}

回答2:

From the WWDC "Introducing Drag and Drop" video it seems that the right place to handle the lift and its cancellation is the dragInteraction(_:willAnimateLiftWith:session:) method.

来源：https://stackoverflow.com/questions/49681643/is-there-a-method-to-check-the-uicollectionview-item-drag-cancellation-if-the-it