UITableView isn't updating when didChangeObject is called NSFetchedResultsController - ios

Question

I'm using an NSFetchedResultsController with my UITableView. I successfully receive delegate calls to - (void)controller:(NSFetchedResultsController *)controller didChangeObject:(id)anObject
atIndexPath:(NSIndexPath *)indexPath forChangeType:(NSFetchedResultsChangeType)type
newIndexPath:(NSIndexPath *)newIndexPath but none of the changes I make to insert/update/delete rows in the UITableView actually show up. I even just try to set the background color on the UITableView to see if any changes will show up, but they don't show up unless I push a new view controller and then pop back. Then I'll see the background color and the table updates.
My implementation of the didChangeObject: method is really just the boilerplate template:
- (void)controllerWillChangeContent:(NSFetchedResultsController *)controller {
[self.tableView beginUpdates];
}
- (void)controllerDidChangeContent:(NSFetchedResultsController *)controller {
[self.tableView endUpdates];
}
- (void)controller:(NSFetchedResultsController *)controller didChangeObject:(id)anObject
atIndexPath:(NSIndexPath *)indexPath forChangeType:(NSFetchedResultsChangeType)type
newIndexPath:(NSIndexPath *)newIndexPath
{
UITableView *tableView = self.tableView;
switch(type) {
case NSFetchedResultsChangeInsert:
[tableView insertRowsAtIndexPaths:#[newIndexPath] withRowAnimation:UITableViewRowAnimationFade];
tableView.backgroundColor = [UIColor redColor];
break;
case NSFetchedResultsChangeDelete:
[tableView deleteRowsAtIndexPaths:#[indexPath] withRowAnimation:UITableViewRowAnimationFade];
break;
case NSFetchedResultsChangeUpdate:
[tableView reloadRowsAtIndexPaths:#[indexPath] withRowAnimation:UITableViewRowAnimationFade];
tableView.backgroundColor = [UIColor blueColor];
break;
case NSFetchedResultsChangeMove:
[tableView deleteRowsAtIndexPaths:#[indexPath] withRowAnimation:UITableViewRowAnimationFade];
[tableView insertRowsAtIndexPaths:#[newIndexPath] withRowAnimation:UITableViewRowAnimationFade];
break;
}
}
I added a button in the navbar with an IBAction which just calls [self.tableView reloadData]; and whenever I tap that, then all of the insertions and updates show up in the table. However, they don't show up as the changes happen.
What is wrong?

Answer 1

It looks like the delegate calls to didChangeObject (and the other methods) are not happening on the Main thread which means they can't update the UI, but those changes were just silently being dropped.
I updated the three methods I included above so that the bodies of those methods were all dispatched on the main thread and everything works as expected. Here is an example below:
dispatch_sync(dispatch_get_main_queue(), ^{
[self.tableView beginUpdates];
});