files in existing app

i remember reading somewhere that if i have an application already in app store i can just update a few data files in itunes for that application, without having to update the entire application ! what's that feature called ? i dont see much discussion around it ! i guess it was introduced in iOS4.0

 

i think there was something like a folder in sandbox csn be marked for sharing, that shows up in itunes, and when we copy files into it and sync, those files are available in application sandbox ! something like that

http://www.raywenderlich.com/1948/how-integrate-itunes-file-sharing-with-your-ios-app

but it seems it cant be tested in simulator, only in devices.

adhoc or dev build ?