This framework implements a strict JSON parser and generator in Objective-C.

JSON (JavaScript Object Notation) is a lightweight data-interchange format. It is easy for humans to read and write. It is easy for machines to parse and generate. [...] JSON is a text format that is completely language independent but uses conventions that are familiar to programmers of the C-family of languages, including C, C++, C#, Java, JavaScript, Perl, Python, and many others. These properties make JSON an ideal data-interchange language. -- http://json.org

Download the framework, embed it in your application, and import the JSON/JSON.h header. You're now ready to make your application speak JSON. The framework adds categories to existing Objective-C objects for a super-simple interface, and provides a JSON class for added control.

Greg Bolsinga has written a post on the mailing list about how you can build an SDK for using this framework on the iPhone. Read it at http://groups.google.com/group/json-framework/browse_thread/thread/5ba7eeffb73c443