[alert addAction:[UIAlertAction
        actionWithTitle:NSLocalizedString(@"Go to Settings", nil)
        style:UIAlertActionStyleDefault
        handler:^(UIAlertAction *action) {
            id observer = [NSNotificationCenter.defaultCenter
                addObserverForName:UIApplicationWillEnterForegroundNotification
                object:nil queue:nil
                usingBlock:^(NSNotification *note) {
                    dispatch_async(dispatch_get_main_queue(), completion);
                    [NSNotificationCenter.defaultCenter removeObserver:observer];
                }];
            if (![UIApplication.sharedApplication openURL:settingsURL]) {
                completion();
                [NSNotificationCenter.defaultCenter removeObserver:observer];
            }
        }]];