That’s not a visual editor, that’s a runtime display. It doesn’t have a screen editor.
Which means I would have to first design screens with pixel math, then look, stop, adjust, look, adjust, look, adjust … that’s one reason I became a back-end developer in the Win32 days because designing frame windows with pixel math was unbearably tedious. There was a dialog resource editor, though, so I always did dialog-box apps when I needed a front end.
If someone wants to pay me to do dual apps I’ll learn it, or learn Xamarin, for now iOS is paying really well.