iOS App Background Task

Here is the code snippet that can be used to execute background tasks on iOS.

Here is the code snippet when you need to run a task in background on an iOS device even when user locks his/her iPhone or iPad or iOS device.

 

Here is the code is written in AppDelegate.cs for background task.

#region background Task
public override void WillEnterForeground(UIApplication application) {
    Console.WriteLine("App will enter foreground");
}
// Runs when the activation transitions from running in the background to
// being the foreground application.
public override void OnActivated(UIApplication application) {
    // Console.WriteLine("App is becoming active");
}
public override void OnResignActivation(UIApplication application) {
    //Console.WriteLine("App moving to inactive state.");
}
public override void DidEnterBackground(UIApplication application) {
    //Console.WriteLine("App entering background state.");
    nint taskID = 0;
    // if you're creating a VOIP application, this is how you set the keep alive
    //UIApplication.SharedApplication.SetKeepAliveTimout(600, () => { /* keep alive handler code*/ });
    // register a long running task, and then start it on a new thread so that this method can return
    taskID = UIApplication.SharedApplication.BeginBackgroundTask(() => {
        Console.WriteLine("Running out of time to complete you background task!");
        UIApplication.SharedApplication.EndBackgroundTask(taskID);
    });
    Task.Factory.StartNew(() => FinishLongRunningTask(taskID));
}
void FinishLongRunningTask(nint taskID) {
    Console.WriteLine("Starting task {0}", taskID);
    Console.WriteLine("Background time remaining: {0}", UIApplication.SharedApplication.BackgroundTimeRemaining);
    // sleep for 15 seconds to simulate a long running task
    Thread.Sleep(15000);
    Console.WriteLine("Task {0} finished", taskID);
    Console.WriteLine("Background time remaining: {0}", UIApplication.SharedApplication.BackgroundTimeRemaining);
    // call our end task
    UIApplication.SharedApplication.EndBackgroundTask(taskID);
}
// [not guaranteed that this will run]
public override void WillTerminate(UIApplication application) {
    Console.WriteLine("App is terminating.");
}#endregion