Swift: mix and match

I’ve been putting off learning Swift for a while. While as a language it is a leap forward from Objective-C, jumping to the Swift wagon from day one wasn’t on my agenda. I wrote Bitenotes with the design from Masaichi Ikeda in Objective-C just to get it to the App Store as early as possible. Hence, I know have a small codebase which I could rewrite from scratch in Swift couple of days but as an exercise I’ll do it incrementally.
I started off with the parser and serializer. Aside from being an interesting learning experience, there was one gotcha: in the Project -> Build Settings -> Packaging, Defines Module was No and Product Module was not defined. That meant that the Xcode generated Swift to Objective-C header file wasn’t being generated.