Interesting. I've worked with a few designers who had Xcode _installed_, but they were mostly using it for the Simulator. Using IB wasn't something they were comfortable with. I'd be really impressed with somebody who's a Sketch/Photoshop wiz coming over to IB and being productive.

On the flip side why would a non-developer bother to install Xcode and learn IB when they can export their ideas directly from Sketch/Photoshop into clickable "prototypes"?