beginBackgroundTaskWithExpirationHandler

We can use beginBackgroundTaskWithExpirationHandler to ensure that a task doesn't get stopped abruptly This is how I used 

- (void)didReceiveObjList:(CFDataRef)message

{

    // Received List Of Objects. Processing the list can take a few seconds.

    // So doing it in separate thread with expiration handler to ensure it gets some time    to do the task even if the app goes to background.

        UIApplication *application = [UIApplication sharedApplication];

__block UIBackgroundTaskIdentifier bgTask = [application beginBackgroundTaskWithExpirationHandler:^{

[application endBackgroundTask:bgTask];

bgTask = UIBackgroundTaskInvalid;

}];

    

dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0), ^{

         [self processObjList:message];

[application endBackgroundTask:bgTask];

bgTask = UIBackgroundTaskInvalid;

});

NSLog(@"Main Thread proceeding...");

}