How to iterate over a JSONObject?

Question

I use a JSON library called JSONObject (I don't mind switching if I need to).

I know how to iterate over JSONArrays, but when I parse JSON data from Facebook I don't get an array, only a JSONObject, but I need to be able to access an item via its index, such as JSONObject[0] to get the first one, and I can't figure out how to do it.

{

   "http://http://url.com/": {

      "id": "http://http://url.com//"

   },

   "http://url2.co/": {

      "id": "http://url2.com//",

      "shares": 16

   }

   ,

   "http://url3.com/": {

      "id": "http://url3.com//",

      "shares": 16

   }

}