I've found that it can be very helpful to be able to load data locally rather than from a server, especially for testing and for situations where you don't have control over the availability or stability of the server side. This code sample shows how, using RestKit, you can load json directly from a file. If you knew what the expected server response was, but didn't have access to the server, this would allow you to put all the object mappings in place and load your object in without requiring a live server. https://gist.github.com/kyleclegg/5846568