gistfile1.mm

- (void)applicationDidFinishLaunching:(NSNotification *)aNotification {
    opQ = [[NSOperationQueue alloc] init];
    [[NSNotificationCenter defaultCenter] addObserverForName:@"CustomOperationCompleted"
             object:nil queue:opQ
        usingBlock:^(NSNotification *notif) {
        NSNumber *theNum = [notif.userInfo objectForKey:@"NumberOfItemsProcessed"];
        NSLog(@"Number of items processed: %i", [theNum intValue]);
    }];
}