iOS Dim background when a view is shown

Question

In my main view, I do some gesture action causing some new view to be shown. At this time I want to dim the entire background (except this new view) as a good UI practice. I

Answer 1

While Dan's suggestion is on target, you cannot use a modal view controller in this case because a typical modal covers the entire screen, blocking the parent view controller, even if you have the background of your view as transparent (you'll see whatever you have in the application's UIWindow).

If you are doing this on the iPad there are 2 modal presentation styles (UIViewModalPresentationStylePageSheet and UIViewModalPresentationStyleFormSheet) that can do something similar, but those will not work on an iPhone or iPod Touch.

Add the "shadow" view, with the dark background and partial opacity and whatever view you want to be in the foreground, to the view controller's view directly. You can animate them in using standard UIView animation blocks, or CoreAnimation.

Another note, if you want to intercept touches to that shadow view you can either make it a giant button, subclass UIView to override one of the touch methods like touchesEnded: or change it to a UIControl which can receive touch events like a UIButton, but without the extra options for text, shadows, states etc.