iPhone app like Twitter design structure

I'm new to iOS development and am working on this app that has a similar interface to the official Twitter app. However, I'm not sure how to organize the view controllers and the hierarchy, especially for UITabBar and UINavigationBar (which one is the parent controller?).

Can you guys point me to the right direction? I started from a blank window-based application project. A list of view controllers in the order of 开发者_StackOverflow中文版the hierarchy would be really helpful. Thank you.

Make the TabBar Controller your root controller. Then, in every tab where you need navigation, use Navigation Controller. It will add Navigation Bars, which you can then modify either in IB (where it applies), or programmatically.