Activity Indicator two or more colors

Hey
I Programm in Visual Studio 2017 with Xamarin
I saw in an example, where their Activity Indicator had two Colors.
it looked as if there were two Activity Indicators one above another and with a litte time difference...
does anyone know how i can implement that?
because when i put two activity indicators at the same place i only can see one...
maybe because they start at the same time? (but i experimented a bit with wait etc so idk)
or maybe because ist not possible?
Thanks