Question

If we have a long running task, we can ensure that the application doesn’t quit until that task is complete by using the following piece of code:

UIApplication *app = [UIApplication sharedApplication];    

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

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

    // Do the work associated with the task, preferably in chunks.

    [app endBackgroundTask:bgTask];
    bgTask = UIBackgroundTaskInvalid;
});

In my case, the applications plist contains an entry for Application does not run in background set to YES. Now, i have a serial queue (dispatch_queue_create(..., NULL)) that logs the operations and perform them one by one. User can post many tasks at a time and it might take couple of seconds 20-30 for all of them to complete.

Now my question is, can i use beginBackgroundTaskWithExpirationHandler with my serial queue? If so, any recommendations as to how? I believe i’ll have to maintain an array of UIBackgroundTaskIdentifier?

Answer 1

To the best of my knowledge, if the application doesn’t support background processing, the application quits immediately. So, starting a background tasks is not possible.