UICollectionViewDiffableDataSource reorderingHandlers not working

Question

Created Sep ’20

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I added the code below to the collectionview using UICollectionViewDiffableDataSource.
However, I can not drag the cells. (mysteriously, I can drag cells on Mac Catalyst)
What is missing?

Code Block swiftdataSource.reorderingHandlers.canReorderItem = { item in return true }
dataSource.reorderingHandlers.didReorder = { [weak self] transaction in
    guard let self = self else { return }
    
    if let updatedBackingStore = self.backingStore.applying(transaction.difference) {
        self.backingStore = updatedBackingStore
    }
}

Answered by frnkwk in 636658022

I found the way to solve it.
Just implement empty UICollectionViewDragDelegate & UICollectionViewDropDelegate methods.

Code Block swiftextension ReorderableCollectionViewController: UICollectionViewDragDelegate {
    func collectionView(_ collectionView: UICollectionView, itemsForBeginning session: UIDragSession, at indexPath: IndexPath) -> [UIDragItem] {
        return []
    }
}
extension ReorderableCollectionViewController: UICollectionViewDropDelegate {
    func collectionView(_ collectionView: UICollectionView, performDropWith coordinator: UICollectionViewDropCoordinator) {
   
 }
}

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Answer 1

frnkwk OP

Sep ’20

Accepted Answer

I found the way to solve it.
Just implement empty UICollectionViewDragDelegate & UICollectionViewDropDelegate methods.

Code Block swiftextension ReorderableCollectionViewController: UICollectionViewDragDelegate {
    func collectionView(_ collectionView: UICollectionView, itemsForBeginning session: UIDragSession, at indexPath: IndexPath) -> [UIDragItem] {
        return []
    }
}
extension ReorderableCollectionViewController: UICollectionViewDropDelegate {
    func collectionView(_ collectionView: UICollectionView, performDropWith coordinator: UICollectionViewDropCoordinator) {
   
 }
}

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