I finally got Playgrounder working more reasonably, as it turns out the Attributed String to HTML functionality I wanted on OS X was there all the time but I needed to include the right frameworks. (Thanks optshiftk). Just open up an RTF file whose swift playground sections are deliminated by ****, and choose Command-1 for iOS and Command-2 for OSX.

Here’s an example I created by copy/pasting from an earlier post.

Download from my utilities page (direct download link)