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PONSFetchedResultsController not firing delegate method after merging update from background thread
 

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    <p>I have an NSFetchedResultsController and a few operations that inserts and updates managed objects on separate threads via NSOperationQueue.</p> <p>The FRC looks like this, note that I have set the cache to nil:</p> <pre><code>[NSFetchedResultsController deleteCacheWithName:nil]; NSFetchedResultsController *aFetchedResultsController = [[NSFetchedResultsController alloc] initWithFetchRequest:fetchRequest managedObjectContext:managedObjectContext sectionNameKeyPath:nil cacheName:nil]; </code></pre> <p>Each threaded operation has its own managed object context and fires mergeChangesFromContextDidSaveNotification to the main MOC each time it saves changes.</p> <p>The code that I use to merge contexts looks like this:</p> <pre><code>- (void)mergeContextChanges:(NSNotification *)notification { NSManagedObjectContext *context = [fetchedResultsController managedObjectContext]; if([NSThread isMainThread] == NO) { [self performSelectorOnMainThread:_cmd withObject:notification waitUntilDone:NO]; return; } NSSet *updated = [[notification userInfo] objectForKey:NSUpdatedObjectsKey]; for(NSManagedObject *thing in updated) { NSLog(@"Background thread updated %@", [thing description]); } for(NSManagedObject *thing in updated) { [[context objectWithID:[thing objectID]] willAccessValueForKey:nil]; } [context mergeChangesFromContextDidSaveNotification:notification]; } </code></pre> <p>I can confirm by looking at the logs that each time the background operations insert or update data, my mergeContextChanges: method is being called with the proper insert/update values.</p> <p>The problem is that while merging <em>inserts</em> are firing the FRCs delegate methods (ex. controllerDidChangeContent:) properly, merging <em>updates</em> doesn't signal the FRC to fire its delegate methods.</p> <p>Strange enough, I can also confirm that the FRC fires its delegates properly if I run the updates on the <em>main thread</em> using the <em>main MOC</em>.</p> <p>How can I make the FRC fire its delegate methods when updated MOCs are merged?</p> <p><strong>More Info:</strong> Looks like using any MOC other than the main MOC and trying to merge <em>updates</em> to the main MOC has the same results; the FRC refuses to notice it.</p>
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