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POIs it possible to have an NSFetchedResultsController delete an object if one of the object's properties doesn't fulfil it's predicate?
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copied!<p>I have an <code>NSFetchedResultsController</code>-backed <code>UICollectionViewController</code> that is populated by a list of objects. Each object has a BOOL property called deleted. My fetch controller uses the following predicate to filter my objects.</p> <pre><code>[NSPredicate predicateWithFormat:@"deleted == NO"]; </code></pre> <p>My issue is that when I delete the object by marking it as <code>deleted = @YES</code>. The subsequent <code>didChangeObject:</code> method tells me that the object was <em>updated</em> and <strong>NOT</strong> <em>deleted</em>. And the object does not get removed from the collection view. If I quit and reload my app, the object does not show up in the collection view, which is the correct behaviour.</p> <p>Is there something that I am doing wrong, or is this the expected behaviour of <code>NSFetchedResultsController</code>?</p> <p><strong>Update as requested here is the code:</strong></p> <p>Fetch controller configuration:</p> <pre><code>NSPredicate *predicate = [NSPredicate predicateWithFormat:@"deleted == %@", @NO]; NSSortDescriptor *timestampSortDescriptor = [[NSSortDescriptor alloc] initWithKey:@"timestamp" ascending:NO]; NSSortDescriptor *prioritySortDescriptor = [[NSSortDescriptor alloc] initWithKey:@"priority" ascending:NO]; NSManagedObjectContext *managedObjectContext = [NSManagedObjectContext MR_defaultContext]; NSFetchRequest *request = [[NSFetchRequest alloc] init]; NSEntityDescription *entity = [NSEntityDescription entityForName:[GYNotification description] inManagedObjectContext:managedObjectContext]; [request setEntity:entity]; [request setIncludesSubentities:YES]; [request setSortDescriptors:sortDescriptors]; [request setPredicate:predicate]; NSFetchedResultsController *aFetchedResultsController = [[NSFetchedResultsController alloc] initWithFetchRequest:request managedObjectContext:managedObjectContext sectionNameKeyPath:sectionNameKeyPath cacheName:nil]; </code></pre> <p>Then the fetch controller delegate methods:</p> <pre><code>- (void)controller:(NSFetchedResultsController *)controller didChangeObject:(id)anObject atIndexPath:(NSIndexPath *)indexPath forChangeType:(NSFetchedResultsChangeType)type newIndexPath:(NSIndexPath *)newIndexPath { NSMutableDictionary *change = [NSMutableDictionary new]; switch(type) { case NSFetchedResultsChangeInsert: change[@(type)] = newIndexPath; break; case NSFetchedResultsChangeDelete: change[@(type)] = indexPath; break; case NSFetchedResultsChangeUpdate: change[@(type)] = indexPath; break; case NSFetchedResultsChangeMove: change[@(type)] = @[indexPath, newIndexPath]; break; } [_objectChanges addObject:change]; } - (void)controllerDidChangeContent:(NSFetchedResultsController *)controller { if ([_objectChanges count] > 0) { [self.collectionView performBatchUpdates:^{ for (NSDictionary *change in _objectChanges) { [change enumerateKeysAndObjectsUsingBlock:^(NSNumber *key, id obj, BOOL *stop) { NSFetchedResultsChangeType type = [key unsignedIntegerValue]; switch (type) { case NSFetchedResultsChangeInsert: [self.collectionView insertItemsAtIndexPaths:@[obj]]; break; case NSFetchedResultsChangeDelete: [self.collectionView deleteItemsAtIndexPaths:@[obj]]; break; case NSFetchedResultsChangeUpdate: [self.collectionView reloadItemsAtIndexPaths:@[obj]]; break; case NSFetchedResultsChangeMove: [self.collectionView moveItemAtIndexPath:obj[0] toIndexPath:obj[1]]; break; } }]; } } completion:nil]; } [_objectChanges removeAllObjects]; } </code></pre>

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