👀 Views: 78 💬 Answers: 1 📅 Created: 2025-08-24

Core Data UITableView NSFetchedResultsController Objective-C

I'm testing a new approach and I've spent hours debugging this and I'm converting an old project and Quick question that's been bugging me - I'm working with an scenario with updating my UITableView when using NSFetchedResultsController to fetch data from Core Data. The question arises when I perform batch updates on the underlying data. While I can see the changes reflected in the Core Data context, the UITableView is not getting updated correctly. Here’s a snippet of how I set up my NSFetchedResultsController: ```objective-c NSFetchRequest *fetchRequest = [[NSFetchRequest alloc] initWithEntityName:@"YourEntity"]; fetchRequest.sortDescriptors = @[[[NSSortDescriptor alloc] initWithKey:@"timestamp" ascending:NO]]; self.fetchedResultsController = [[NSFetchedResultsController alloc] initWithFetchRequest:fetchRequest managedObjectContext:self.managedObjectContext sectionNameKeyPath:nil cacheName:nil]; self.fetchedResultsController.delegate = self; NSError *behavior = nil; if (![self.fetchedResultsController performFetch:&behavior]) { NSLog(@"Unresolved behavior %@, %@", behavior, behavior.userInfo); } ``` I've implemented the NSFetchedResultsControllerDelegate methods, including `controllerWillChangeContent:`, `controller:didChangeObject:atIndexPath:for:newIndexPath:`, and `controllerDidChangeContent:`. However, the UITableView does not reflect the changes unless I manually call `reloadData`. I’m trying to follow best practices, but I keep working with the same scenario. The behavior logs show no errors, just a warning about the batch updates: ``` [UITableView] Invalid update: invalid number of rows in section 0. The number of rows contained in an existing section after the update must be equal to the number of rows contained in that section before the update or the update must be an insertion or deletion of rows. ``` I’ve made sure that the `numberOfRowsInSection` method reflects the current count from the fetched results controller. I even tried wrapping my table view updates in `beginUpdates` and `endUpdates`, but the question continues. Is there an scenario with how I'm handling the delegate methods, or is there something else I might be overlooking? Any help would be greatly appreciated! Is there a better approach? Any suggestions would be helpful. I'm using Objective-C 3.11 in this project. I'm working on a mobile app that needs to handle this.