# reorderingHandlers The diffable data source’s handlers for reordering items. ``` @MainActor @preconcurrency var reorderingHandlers: UICollectionViewDiffableDataSource.ReorderingHandlers { get set } ``` ## Discussion Provide reordering handlers to support the reordering of items in your collection view. The system calls the [`didReorder`](/documentation/UIKit/UICollectionViewDiffableDataSource-9tqpa/ReorderingHandlers-swift.struct/didReorder) handler after a reordering transaction ([`NSDiffableDataSourceTransaction`](/documentation/UIKit/NSDiffableDataSourceTransaction-swift.struct)) occurs, so you can update your data backing store with information about the changes. ```swift // Allow every item to be reordered dataSource.reorderingHandlers.canReorderItem = { item in return true } // Option 1: Update the backing store from a CollectionDifference dataSource.reorderingHandlers.didReorder = { [weak self] transaction in guard let self = self else { return } if let updatedBackingStore = self.backingStore.applying(transaction.difference) { self.backingStore = updatedBackingStore } } // Option 2: Update the backing store from the final item identifiers dataSource.reorderingHandlers.didReorder = { [weak self] transaction in guard let self = self else { return } self.backingStore = transaction.finalSnapshot.itemIdentifiers } ``` --- Copyright © 2026 Apple Inc. All rights reserved. | [Terms of Use](https://www.apple.com/legal/internet-services/terms/site.html) | [Privacy Policy](https://www.apple.com/privacy/privacy-policy)