Agreed. I am yet to formally make my app available but had tough times mainly while doing Ajax calls, typecasting the JSON i got. Infact took time to understand some concepts like ARC, Optional Chaining when you are from JS background.
This is where a typed serialization comes in handy. (Protobufs, Thrift, Cap'n Proto, etc.) It is also possible to use an IDL to generate a type-safe API to deal with JSON -- although I don't know of any tools that emit Swift. Interfacing with third-party JSON APIs can be a pain though.
