While developing our titles with cocos2d-x, we use protobuf library a lot for class serialization and persistance. Protocol buffers are a flexible, efficient, automated mechanism for serializing structured data – think XML, but smaller, faster, and simpler. As Google puts it: “Protocol buffers are now Google’s lingua franca for data”. You can check out the documentation here: https://developers.google.com/protocol-buffers/docs/overview
This is the first part of a two part tutorial on how to use protocol buffers with iOS/Android with cocos2d-x, so here is the iOS part: http://www.giraffe-games.com/using-protobuf-protocol-buffers-on-iphone-ios/