iPhone app server communication XML or JSON?

Which method is easier and more efficient? XM开发者_如何学JAVAL or Json Where can I find a tutorial and code samples for each?

---

I recently learned how to use JSON on the iPhone and it was very easy.

Here's a framework:

http://code.google.com/p/json-framework/

General JSON info can be found here:

http://www.json.org/