How to show a Loading Message in Xamarin.Forms (for all platforms)?

Hi
I have created my (first) app based on the template Blank App (Xamarin.Forms Shared).

I now have implemented the access to our WebService to query data.
-> This seems to work with all platforms :-)

Unfortunately there is no "Loading Message" with "spinning wheel" or something similar displayed automatically while the webservice is called.
Now I want to add such a Loading Message.

Is there a way to implement this with Xamarin.Forms?

-> One Implementation that works with all platforms ?

Thanks