How to scroll an Action Sheet?

I'm sure lots of people must have used DIsplayActionSheet in their apps. Has anybody then gone on to automate the testing of it using Xamarin.UITest? If so, could you share how you automated the scrolling of the action sheets please? (I'm looking at iOS at the moment). I can get the action sheet to scroll, but cannot see how to specify what it should scroll to (there doesn't appear to be an option to specify "within" other than using Marked, but Xamarin.Forms doesn't appear to provide a mechanism to specify the values on an action sheet that Marked would look at).

Thanks,

John H.