See the example code for parsing JSON to Core Data locally here on Github: https://github.com/jterhorst/LargeCoreDataExample
In the video, I explain how/why I set it up some of it the way I did. The example JSON file is included.
If you need to pull the JSON from a web server somewhere, I suggest using AFNetworking (https://github.com/AFNetworking/AFNetworking), or read up on NSURLConnection or NSURLSession. Those aren't covered in this example, but they aren't too difficult to figure out after you've understood Core Data.
JSON was generated with json-generator.com.