# controllerWillChangeContent(_:) Notifies the receiver that the fetched results controller is about to start processing of one or more changes due to an add, remove, move, or update. ``` optional func controllerWillChangeContent(_ controller: NSFetchedResultsController) ``` ## Parameters `controller` The fetched results controller that sent the message. ## Discussion This method is invoked before all invocations of [`controller(_:didChange:at:for:newIndexPath:)`](/documentation/CoreData/NSFetchedResultsControllerDelegate/controller(_:didChange:at:for:newIndexPath:)) and [`controller(_:didChange:atSectionIndex:for:)`](/documentation/CoreData/NSFetchedResultsControllerDelegate/controller(_:didChange:atSectionIndex:for:)) have been sent for a given change event (such as the controller receiving a notification). ## See Also [Core Data Programming Guide](https://developer.apple.com/library/archive/documentation/Cocoa/Conceptual/CoreData/index.html#//apple_ref/doc/uid/TP40001075) --- 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)