iOS How to add a file (text or image) to iphone app through itunes?

Hi,

Is there any way to add a file (image or text) to already install app in the iphone through itunes (or any other way)?

I'm working on an app, in which I want to add a feature for adding external file (like text or image file).

Please help me, how can I achieve this?

Or it is not possible in current SDK?

Note : I don't want to do this through downloading from internet.

Thanks