Могу ли я поместить цикл в dispatch_async, когда мое приложение переходит в фоновый режим?

Я хочу создать приложение для iOS. Идея состоит в том, чтобы запустить UILocalNotification, когда состояние вызова Connected. Я пытаюсь использовать dispatch_async блок в методе applicationDidEnterBackground и помещаю в этот блок цикл while(!isConnected), чтобы узнать, когда должен быть запущен UILocalNotificacion. Цикл проверяет состояние вызова и решает, когда запускать уведомление.

Что мне нужно знать, это правильный способ решить мою проблему? или у кого-нибудь есть идея получше?

Хорошо, это мой код:

- (void)applicationDidEnterBackground:(UIApplication *)application
 {

// Use this method to release shared resources, save user data, invalidate timers, and store enough application state information to restore your application to its current state in case it is terminated later.
// If your application supports background execution, this method is called instead of applicationWillTerminate: when the user quits.
isAlive = YES;

NSLog(@"BackgroundTimerRemaining %f", [application backgroundTimeRemaining]);

// verufy status of call
bgTask = [application beginBackgroundTaskWithExpirationHandler:^{
    // Clean up any unfinished task business by marking where you
    // stopped or ending the task outright.
    [application endBackgroundTask:bgTask];
    bgTask = UIBackgroundTaskInvalid;
}];

[self readLocalVariableCalling];

__block int connected = 0;

__block int callingTemp = 1;//((NSNumber*)[self.datos objectForKey:@"calling"]).intValue;
NSLog(@"callingTemp: %d", callingTemp);

__strong typeof(self) weakSelf = self;

// Start the long-running task and return immediately.
dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0), ^{

    @autoreleasepool
    {
        //isAlive = YES;
        // Do the work associated with the task, preferably in chunks.
        while (callingTemp == 1)
        {
            if (callCenter != nil)
            {

            callCenter.callEventHandler = ^(CTCall* call)
            {
                NSLog(@"Loop - Call EventHandler state: %@", call.callState);
                if([call.callState isEqualToString:CTCallStateDisconnected])
                {

                    NSLog(@"disconnected");
                    [[UIApplication sharedApplication] cancelAllLocalNotifications];
                    callingTemp = 0;
                    connected = 0;
                    [weakSelf.datos setObject:[NSNumber numberWithInt:0] forKey:@"calling"];
                    [weakSelf saveLocalVariableCalling];

                }
                if ([call.callState isEqualToString:CTCallStateDialing] &&
                    connected == 0)
                {
                    NSLog(@"connected - Call EventHandler state : %@", call.callState);
                    connected = 1;
                    if (callingTemp == 1
                        && weakSelf.timerTableViewController.currentTimer)
                    {

                        TimeDto *currentTimer = weakSelf.timerTableViewController.currentTimer;
                        NSInteger seconds = currentTimer.value.intValue;

                        NSLog(@"minutos a segundos = %d", seconds);

                        NSDate *alertTime = [[NSDate date] dateByAddingTimeInterval:seconds];
                        UIApplication* app = [UIApplication sharedApplication];

                        if (weakSelf.notifyAlarm)
                        {
                            weakSelf.notifyAlarm.fireDate = alertTime;
                            weakSelf.notifyAlarm.timeZone = [NSTimeZone defaultTimeZone];
                            weakSelf.notifyAlarm.repeatInterval = 0;
                            weakSelf.notifyAlarm.soundName = @"road.caf";

                            NSString *messageTimer = NSLocalizedString(@"messageTimer", nil);
                            weakSelf.notifyAlarm.alertBody = [NSString stringWithFormat:messageTimer, ((int)currentTimer.value.intValue / 60 ) , (currentTimer.value.intValue % 60)];

                            [app scheduleLocalNotification:weakSelf.notifyAlarm];
                        }
                    }
                }


            };
            }
            else
            {
                NSLog(@"callCenter is null");
            }
            //NSLog(@"loop call state");

        }

        NSLog(@"Call Finished");


        [application endBackgroundTask:bgTask];
        bgTask = UIBackgroundTaskInvalid;
    }

});
}