<AbsoluteLayout>
  <StackLayout HorizontalOptions="FillAndExpand" VerticalOptions="FillAndExpand" AbsoluteLayout.LayoutBounds="0, 0, 1, 1"
  AbsoluteLayout.LayoutFlags="All" Padding="30" >
  <Grid>
   //something
  </Grid>
  <ContentView x:Name="overlay" AbsoluteLayout.LayoutBounds="0, 0, 1, 1"  AbsoluteLayout.LayoutFlags="All" IsVisible="False" BackgroundColor="#C0808080" Padding="10, 0">
    <ActivityIndicator  WidthRequest="110" HeightRequest="70" IsRunning="True" IsVisible="True" Color="Black" HorizontalOptions="CenterAndExpand" VerticalOptions="CenterAndExpand"/>
  </ContentView>
</AbsoluteLayout>