Piictu: How did they build the UI?

Just came across the Piictu iOS app (Screenshot).

The UI looks great and I was wondering how they did it and what elements they used.

Is it a UINavigationController with a custom navigationBar and 开发者_如何学PythontoolBar? Or did they use a UITabbarController?

The left button in the detail view toggles between an overview and a more detailed view, which makes me think they used a UINavigationController with a custom background and two buttons...

I think you have the right idea. Looks like a navigation controller with a customized nav bar (see http://idevrecipes.com/2011/01/12/how-do-iphone-apps-instagramreederdailybooth-implement-custom-navigationbar-with-variable-width-back-buttons/ for an example) and either a custom toolbar or just a UIView containing a couple of buttons.