We have also used the core of this to create an IO class for saving state to disk and back. You can find it here:

https://github.com/uacaps/NSObject-ObjectIO

It's a one liner to save complex objects (see demos) with encryption. We used AES-256 encryption with PBKDF2 for the key gen. That said, we would be more than happy to hear reviews on the efficacy of our method. Thanks!

This looks very good, similar to RestKit but alot more flexible. Good Work