title: How to show ActivityIndicator in the middle of the screen?
body: <p>I've created an activity indicator and added it to StackLayout and when I make it running, in the emulator it shows in the top right corner Android 4.4 and in iOS no show and in Android 6 phone, it don't show.</p>
  
  <pre><code>var indicator = new ActivityIndicator()
              {
                  Color = Color.Blue,
              };
              indicator.SetBinding(ActivityIndicator.IsVisibleProperty, "IsBusy", BindingMode.OneWay);
              indicator.SetBinding(ActivityIndicator.IsRunningProperty, "IsBusy", BindingMode.OneWay);
  AbsoluteLayout.SetLayoutFlags(indicator, AbsoluteLayoutFlags.PositionProportional);
              AbsoluteLayout.SetLayoutBounds(indicator, new Rectangle(0.5, 0.5, AbsoluteLayout.AutoSize, AbsoluteLayout.AutoSize));
  mainLayout.Children.Add(indicator);
  </code></pre>
  
  <p>I want to show the activity indicator to the center of the screen because the operation takes time to complete.</p>