Asynchronous tasks

All apps need to perform tasks that may take longer than a few milliseconds. If a task blocks the UI thread for longer than a few seconds, Android will terminate it, crashing the application.

How to do it...

If we want to do work in the background, we use a new thread. To do this, we make use of the Task Parallel Library (TPL) and the async/await keywords:

1. The first thing that is needed is the method that we wish to execute:

   public async Task DoWorkAsync() {
     await Task.Run(() => {
       // some long running task
     });
   }

2. We then invoke it like a normal method, but just with the await keyword:

   await DoWorkAsync();

3. We can also attach it to an event:

   doWork.Click += async (sender, args) => {
     await DoWorkAsync();
   }

4. We can also override the void methods by simply inserting the async keyword before the return type:

   protected override async void OnCreate(Bundle bundle) {
     base.OnCreate(bundle);
     await DoWorkAsync();
   }

5. If the method needs to return a value, we use Task<>:...