A couple blog posts back I gave you a quick peek at our support for UIKit for Mac (a.k.a. Project Catalyst, or Marzipan) in Elements. It's really easy to get your iOS app running on macOS Catalina with just a single setting change (but of course you'll want to imrpove it beyond that, to make a good Mac app).
We've now put together a short (less than 3 minutes) video that shows you UIKit for Mac with Elements in action:
You can watch the video embedded above, on YouTube or on RemObjects TV. The latter link also has the full transcript, and both versions have close captions so you can follow along without audio, if needed.