UITableViewCell with UICollectionView - core-data

Question

I'm following this tutorial Creating a Scrolling Filmstrip Within a UITableView
but instead of using static array i'm using core data with nsfetchresultscontroller i have a problem with delegate
- (NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section {
return 1;
}
i want to return only one item per cell which contains all items inside:
- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath
{
ContainerCell *cell = [tableView dequeueReusableCellWithIdentifier:#"ContainerCell"];
NSArray *items = [[[self.frc sections] objectAtIndex:indexPath.section] objects];
[cell setCollectionData:items];
return cell;
}
but i'm getting this error:
CoreData: error: Serious application error. An exception was caught from the delegate of NSFetchedResultsController during a call to -controllerDidChangeContent:. attempt to delete row 1 from section 9 which only contains 1 rows before the update with userInfo (null)
if i'm using
- (NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section {
NSInteger rows = [super tableView:tableView numberOfRowsInSection:section];
return rows;
}
the app is not crashing but i'm getting duplicates per cell
any ideas how to fix this
Thanks

Answer 1

You are using non-standard numbers of rows in your sections, so you have to make sure that when the underlying data changes, the appropriate number of rows is deleted and added. In your case, none.
Look for the delegate method in your controller where the rows are erroneously deleted or added. It is mentioned in your error message and should be
- (void)controller:(NSFetchedResultsController *)controller didChangeObject:(id)anObject
atIndexPath:(NSIndexPath *)indexPath forChangeType:(NSFetchedResultsChangeType)type
newIndexPath:(NSIndexPath *)newIndexPath
As you can see, in the delete case, it does this:
case NSFetchedResultsChangeDelete:
[tableView deleteRowsAtIndexPaths:#[indexPath]
withRowAnimation:UITableViewRowAnimationFade];
break;
But the indexPath is not describing the position of your managed object in the table view because you are displaying all rows of a section in a single row. So you can simply delete this line and replace it with the appropriate reload function for the first row in the section. Maybe you have a configureCell method as in the Xcode boilerplate code:
NSIndexPath *row = [NSIndexPath indexPathForRow:0 inSection:indexPath.section];
[tableView configureCell:[tableView cellForRowAtIndexPath:row] atIndexPath:row];