If you do any native iPhone development, check out ASIHttpRequest. You’ll be glad you did. I tried a couple of frameworks, Objective Resource and HttpRiot before using this library. I found that using a library for making HTTP requests feels much more natural to me than using a framework. ASIHttpRequest reminds me of jQuery’s ajax() function.
Perhaps when I’m working with a large number of models I’ll want something like Objective Resource or HttpRiot. If I do, I’ll consider changing one of them to be an interface to ASIHttpRequest, which builds upon lower-level APIs to be more powerful than NSUrlRequest.