I got a JSON response with a lot of data.
(e.g.: Private Messages).
How to display them into a table?
I mean in C#.net I normaly would have a class (PM) with a lot of Properties (sender, reciever, subject, text) and make a database-query (here JSON) and fill it in a list of my class (List pmList = new pmLIst();).
How to do it in Objective C for iPhone?
Have a look at SBJson. The TweetStream example project shows how to fetch data over an HTTP connection and parse it. If the data contains a list of objects you’ll find those in an NSArray in your parsed data; at that point it’s simply a matter of using a UITableView to display the data.