Why does Task.WaitAll() not block or cause a deadlock here?

Question

In the example below two await calls are used. To gain performance, the sample gets converted Task.WaitAll() instead (not really any faster, but th

Answer 1

Maybe this sample will demonstrate what might be happening. It's an iOS view loading. Try it with both the await call and without it (commented out below). Without any await in the function it will run synchronously and the UI will be blocked.

    public async override void ViewDidLoad()
    {
        base.ViewDidLoad ();

        var d1 = Task.Delay (10);
        var d2 = Task.Delay (10000);

        //await Task.Delay (10);

        Task.WaitAll (d1, d2);

        this.label.Text = "Tasks have ended - really!";
    }

    public override void ViewWillAppear(bool animated)
    {
        base.ViewWillAppear (animated);
        this.label.Text = "Tasks have ended - or have they?";
    }