Example how I use CoreData & Networking

AppDelegate.m

/*
AppDelegate.m
*/

- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions { 

    [[NSNotificationCenter defaultCenter] addObserverForName:NSManagedObjectContextDidSaveNotification object:nil queue:[NSOperationQueue mainQueue] usingBlock:^(NSNotification *note){
		[self.managedObjectContext mergeChangesFromContextDidSaveNotification:note];
	}];

    DataController *adapter = [DataController sharedDataController];
    adapter.persistentStoreCoordinator = self.persistentStoreCoordinator;
    adapter.managedObjectContext = self.managedObjectContext;

}

DataController.m

/*
DataController.m
*/

- (void)refresh {
    //dataAdapter = NetworkController, loads & returns parsed JSON
    [self.dataAdapter refreshWithCompletionHandler:^(NSArray *items, NSError *error) {
        NSLog(@"Loaded items: %@", items);
        
        dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0), ^{
            
            if (!items || [items isKindOfClass:[NSNull class]] || [items count] < 1) return;
            
            NSManagedObjectContext *moc = [[NSManagedObjectContext alloc] init];
            [moc setPersistentStoreCoordinator:self.persistentStoreCoordinator];
            
            NSEntityDescription *albumEntity = [NSEntityDescription entityForName:@"Album" inManagedObjectContext:moc];
            
и тд
            
            NSError *error;
            if (![moc save:&error]) {
                NSLog(@"Error saving DB: %@, %@", [error localizedDescription], [error userInfo]);
            }
            [moc release];
            
        });
        
    }];

}

ViewController.m

/*
ViewController.m (subclass from UITableViewControler)
Using Table & NSFetchedResultController
delegate=self
*/

- (IBAction)refresh {
    DataController *adapter = [DataController sharedDataController];
    [adapter refresh];
}

- (void)controllerDidChangeContent:(NSFetchedResultsController *)controller {
    //[self.itemsTableView endUpdates];
    //NSLog(@"loaded");
    [self removeLoadingView];
    [self.itemsTableView reloadData];
}