Brent Simmons of Inessential.com on Apple’s implementation of UXKit in the new Photos.app beta:
The point would be to make cross-platform development a little quicker — but it wouldn’t get you out of using UIKit and AppKit.
Imagine how cool it would be to know one language, but simultaneously ‘develop’ for multiple platforms? An iOS app and an OS X app, but without the headache. It doesn’t sound like UXKit will be that, but maybe this is a step in that direction?