# controller(_:didChangeContentWith:) Notifies the receiver about changes to the content in the fetched results controller, by using a collection difference. ``` optional func controller(_ controller: NSFetchedResultsController, didChangeContentWith diff: CollectionDifference) ``` ## Discussion This method is only invoked if the controller’s [`sectionNameKeyPath`](/documentation/CoreData/NSFetchedResultsController/sectionNameKeyPath) property is `nil` and [`controller(_:didChangeContentWith:)`](/documentation/CoreData/NSFetchedResultsControllerDelegate/controller(_:didChangeContentWith:)-4kezq) is not implemented. If this method is implemented, no other delegate methods are invoked. --- 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)