NSFetchedResultsController: sectionNameKeyPath not tracked for changes?

Question

My database model has a MainCategory entity and a SpendingCategory entity. Here I group by the MainCategory.position. But if these positions are changed no changes happen in the results of this NSFetchedResultsController. How can I track these changes with this FetchedResultsController?

    self.managedObjectContext = ((AppDelegate *)[[UIApplication sharedApplication] delegate]).managedObjectContext;

    NSFetchRequest *request = [NSFetchRequest fetchRequestWithEntityName:@"SpendingCategory"];

    NSSortDescriptor *mainCatPosition = [[NSSortDescriptor alloc]
                            initWithKey:@"belongsToMainCategory.position" ascending:YES];
    NSSortDescriptor *spendingCatPosition = [[NSSortDescriptor alloc]
                            initWithKey:@"position" ascending:YES];

    request.sortDescriptors = [NSArray arrayWithObjects:mainCatPosition,spendingCatPosition,nil];
    request.predicate = [NSPredicate predicateWithFormat:@"liveBudget = %@", [NSNumber numberWithBool:YES]];

    self.fetchedResultsController = [[NSFetchedResultsController alloc]initWithFetchRequest:request
                                                                       managedObjectContext:self.managedObjectContext
                                                                         sectionNameKeyPath:@"belongsToMainCategory.position"
                                                                                  cacheName:nil];

EDIT:

- (void)controller:(NSFetchedResultsController *)controller
  didChangeSection:(id <NSFetchedResultsSectionInfo>)sectionInfo
           atIndex:(NSUInteger)sectionIndex
     forChangeType:(NSFetchedResultsChangeType)type
{
    if(!self.reordering){
        if (!self.suspendAutomaticTrackingOfChangesInManagedObjectContext)
        {
            switch(type)
            {
                case NSFetchedResultsChangeInsert:
                    [self.tableView insertSections:[NSIndexSet indexSetWithIndex:sectionIndex] withRowAnimation:UITableViewRowAnimationFade];
                    break;

                case NSFetchedResultsChangeDelete:
                    [self.tableView deleteSections:[NSIndexSet indexSetWithIndex:sectionIndex] withRowAnimation:UITableViewRowAnimationFade];
                    break;
            }
        }
    }
}

have you implemented delegate? i.e self.fetchedResultsController.delegate = self; — Manish Agrawal, Jan 01 '14 at 12:15

score 0 · Answer 1 · answered Jan 01 '14 at 12:07

0

You have to implement the NSFetchedResultsControllerDelegate. Implement the call back that deals specifically with sections:

controller:didChangeSection:atIndex:forChangeType:

answered Jan 01 '14 at 12:07

Mundi

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Thx see my edit, thats the method in my CoreDataViewController (parent class of all my View controllers using NSFetchedResultsController). But nothing happens, even though method is called correctly. – MichiZH Jan 01 '14 at 12:13
It follows, that your if statements do not evaluate as expected. – Mundi Jan 01 '14 at 12:36
The delegate is fine. The problem is that (bizarrely, one of the strangest things in all of Apple) core data does not work with relationships - relationships do NOT update in fetched results controllers - only the "main" entity triggers updates. – Fattie Feb 29 '20 at 14:05

NSFetchedResultsController: sectionNameKeyPath not tracked for changes?

1 Answers1