Question

My table view shows a list of users. I’m having issues refreshing my table view after adding a user. I’ve tried different combinations of code and events and now the app is crashing on the endUpdates call. The app is modeled after the recipe app, so a user clicks the add button, and then a modal window appears asking for the users name. Then it goes to the edit screen, and then back to the list of users. At that point, the new user wasn’t showing up. But if I navigated back to the main screen, and then back to the users screen, the user would appear.

Here’s some of my code:

    - (void)controllerWillChangeContent:(NSFetchedResultsController *)controller {
    sectionInsertCount = 0;
    [self.tableView beginUpdates];
}
- (void)controllerDidChangeContent:(NSFetchedResultsController *)controller {
  [self.tableView endUpdates];

}

    - (void)controller:(NSFetchedResultsController *)controller didChangeSection:(id <NSFetchedResultsSectionInfo>)sectionInfo atIndex:(NSUInteger)sectionIndex forChangeType:(NSFetchedResultsChangeType)type {
 switch(type) {

  case NSFetchedResultsChangeInsert:
            if (!((sectionIndex == 0) && ([self.tableView numberOfSections] == 1))) {
                [self.tableView insertSections:[NSIndexSet indexSetWithIndex:sectionIndex] withRowAnimation:UITableViewRowAnimationFade];
                sectionInsertCount++;
            }

   break;
  case NSFetchedResultsChangeDelete:
            if (!((sectionIndex == 0) && ([self.tableView numberOfSections] == 1) )) {
                [self.tableView deleteSections:[NSIndexSet indexSetWithIndex:sectionIndex] withRowAnimation:UITableViewRowAnimationFade];
                sectionInsertCount--;
            }

   break;
        case NSFetchedResultsChangeMove:
            break;
        case NSFetchedResultsChangeUpdate: 
            break;
        default:
            break;
 }
}

    - (void)controller:(NSFetchedResultsController *)controller didChangeObject:(id)anObject atIndexPath:(NSIndexPath *)indexPath forChangeType:(NSFetchedResultsChangeType)type newIndexPath:(NSIndexPath *)newIndexPath {
 switch(type) {
  case NSFetchedResultsChangeInsert:
            [self.tableView insertRowsAtIndexPaths:[NSArray arrayWithObject:newIndexPath] withRowAnimation:UITableViewRowAnimationFade];
   break;
  case NSFetchedResultsChangeDelete:
   [self.tableView deleteRowsAtIndexPaths:[NSArray arrayWithObject:indexPath] withRowAnimation:UITableViewRowAnimationFade];
   break;
        case NSFetchedResultsChangeUpdate: {
            [self.tableView reloadRowsAtIndexPaths:[NSArray arrayWithObject:indexPath] withRowAnimation:UITableViewRowAnimationFade];
        }
  case NSFetchedResultsChangeMove:
            if (newIndexPath != nil) {

                NSUInteger tableSectionCount = [self.tableView numberOfSections];
                NSUInteger frcSectionCount = [[controller sections] count];
                if (frcSectionCount != tableSectionCount + sectionInsertCount)  {
                    [self.tableView insertSections:[NSIndexSet indexSetWithIndex:[newIndexPath section]] withRowAnimation:UITableViewRowAnimationNone];
                    sectionInsertCount++;
                }


                [self.tableView deleteRowsAtIndexPaths:[NSArray arrayWithObject:indexPath] withRowAnimation:UITableViewRowAnimationFade];
                [self.tableView insertRowsAtIndexPaths: [NSArray arrayWithObject:newIndexPath]
                                     withRowAnimation: UITableViewRowAnimationRight];

    runEndUpdates = NO;

            }
            else {
                [self.tableView reloadSections:[NSIndexSet indexSetWithIndex:[indexPath section]] withRowAnimation:UITableViewRowAnimationFade];
            }
   break;
        default:
   break;
 }
}

I’m almost at a breaking point with this. CoreData has been the most frustrating part of app development. Should I just switch to SQL Lite? Or will I still have the same issues?

Thanks!

Answer 1

Today I had the very same issue.

The problem was in my source code – one of UITableViewDataSource functions used invalid object (not CoreData object, simple array, which I forgot to retain), this caused crash. Unfortunately this was not clear from the call stack, no message was provided in the console.

So the reason might be in your implementation of UITableViewDataSource protocol.