That's what Xamarin.Forms (https://www.xamarin.com/forms https://www.xamarin.com/forms) does, for iOS, Android and UWP (desktop, mobile, xbox). My preference is

That's what Xamarin.Forms (https://www.xamarin.com/forms https://www.xamarin.com/forms) does, for iOS, Android and UWP (desktop, mobile, xbox). My preference is still to go the native UI route though. If you take an MVVM approach, you'll naturally keep the logic in the shared code - the models and viewmodels - and you then can build views specifically for each platform and bind them on.