mergeChangesFromContextDidSaveNotification with core data bug workarounds

gistfile1.txt

// See http://lists.apple.com/archives/cocoa-dev/2008/Jun/msg00237.html for bugs below
- (void)mergeChangesFromContextDidSaveNotification:(NSNotification*)notification {
    NSManagedObject *object;
    NSSet* updates;
    
	// Workaround bug 5982319
    // Fault in all updated objects because chnages to faults won't trigger fetchedResultsControlle
    updates = [notification.userInfo objectForKey:NSUpdatedObjectsKey];
	for (object in updates) {
		[[self.roManagedObjectContext objectWithID:[object objectID]] willAccessValueForKey:nil];
	}

    [self.roManagedObjectContext mergeChangesFromContextDidSaveNotification:notification];
    
    // Workaround for bug 5937572
    // Clean up unexpected 'maintainance' after merge.
    // mergeChangesFromContextDidSaveNotification tries to maintain the object models relations
    // and messes it up. As we only merge consistent changes into a clean context no 'after merge'
    // maintainance is needed. We can safely revert all changes.
    // To still fire all changes, processPendingChanges must be called first though.
    updates = self.roManagedObjectContext.updatedObjects;
    for (object in updates) {
        [self.roManagedObjectContext refreshObject:object mergeChanges:NO];
    }
    // Save the remaining changes (deletes) to get our context clean again
    NSError *error = nil;
    self.inCleanup = YES;
    [self.roManagedObjectContext save:&error];
    self.inCleanup = NO;
    if (error) {
        PRLog(@"Error saving merged changes: %@", error);
    }
}

- (void)contextDidSave:(NSNotification *)notification {
    NSManagedObjectContext *savingContext = (NSManagedObjectContext *) [notification object];

    if (savingContext.persistentStoreCoordinator != self.persistentStoreCoordinator) {
        // Ignore saving of contexts on different store coordinators
        return;
    }    
    if (self.roManagedObjectContext == savingContext) {
        if (!self.inCleanup) {
            PRLog(@"####### Write operation on roManagedObjectContext detected !!!!!!");
        }
        // No need to merge chnages from our our own context
        return;
    }
    if (dispatch_get_current_queue() != self.writeQueue) {
        PRLog(@"####### Write operation on wrong queue detected !!!!!!");
    }
    [self performSelectorOnMainThread:@selector(mergeChangesFromContextDidSaveNotification:) 
                                                  withObject:notification waitUntilDone:YES];
}