UITableView transition when drilling down

I saw this amazing transition in an app: when the user clicks on an item in the tableview 开发者_StackOverflow中文版and it "drills down" the transition is done "on top" of a background. That is the background image is static and just the actual tableview and whatever is presented after pressing something is moving (from right to left as usual).

How is this layered tableview transition done? Anyone knows?

(the app is "Munch-5-a-day" in the info-view)

---

Endemic gives you the right direction. Another way can be view controllers with transparent background and then customize UIWindow.

---

UINavigationController is a subclass of the standard UIViewController class, so it inherits the view property of UIViewController. I would imagine that the background image transition consists of two important steps:

1. Assign a UIImageView containing the desired background image to the view property of the NavController
2. Set self.view.backgroundColor = [UIColor clearColor] in each ViewController, most likely in the viewDidLoad method.

I'm currently unable to test this, but it should work.

Reference: UINavigationController Class Reference