How to run on UI Thread

Hello,

I'm in trouble to run a portion of code on Ui Thread from shared code. Basically in shared code I download a Json using HttpWebRequest. Parsed Json, the code fails when updating ListView throwing a cross thread exception. This should be fixed running the init og ListView into Ui thread but not found how to do it.

I read "Invoking on the UI Thread" from here: http://developer.xamarin.com/guides/cross-platform/application_fundamentals/building_cross_platform_applications/part_5_-_practical_code_sharing_strategies/

Anyway it seems is not useful.

Thanks