Xamarin iOS: BackgroundTask, Do I need to set task object to invalid

Question

I am using the background task. The task working fine but will force close at some point. I have test application and keep it open for whole afternoon, if I remove the background task I have in the code, the crash didn't happen.

After I looked closely, probably missing a line of code to assign the task object invalid.

var siteId = Settings.CurrentSiteId;
        if (siteId > 0 && !(new EntityBLL().IsInitial(siteId)))
        {
            var task = nint.MinValue;
            task = UIApplication.SharedApplication.BeginBackgroundTask("bgEntityDownload", () =>
            {
                ServerEntity.TerminateAutoDownload(true);
                UIApplication.SharedApplication.EndBackgroundTask(task);
                task = UIApplication.BackgroundTaskInvalid;

                completionHandler?.Invoke(UIBackgroundFetchResult.NewData);
            });

            AppLogger.Instance.AddLog(AppLogLevel.Information,
                                      nameof(TimerDownload),
                                      nameof(DownloadEntityFromServer),
                                      "Background download starts", "");

            var result = await ServerEntity.AutoDownload(siteId);
            UIApplication.SharedApplication.EndBackgroundTask(task);
            task = UIApplication.BackgroundTaskInvalid;

            completionHandler?.Invoke(UIBackgroundFetchResult.NewData);
        }

The line here :

var result = await ServerEntity.AutoDownload(siteId);
            UIApplication.SharedApplication.EndBackgroundTask(task);
            task = UIApplication.BackgroundTaskInvalid;

Is the line with task = UIApplicaition.BackgroundTaskInvalid is required after the work done.

Answer 1

It's not required, but a good practice that allows a system to spend its resources on different processes. Your background task will be force terminated after 180 seconds.