How to block UI in IPhone

How c开发者_如何学JAVAan I block UI thread without using sleep?

Just to be clear: I understand that UI will freeze for user, but that is the idea.

Can I run empty RunLoops? Any other ways.

If you just want to block all interaction with your UI, call the UIApplication method -beginIgnoringInteractionEvents. If you're actually trying to prevent the entire UI from doing anything (which is not a good idea—your application might block the appearance of a system notification, for instance), then yes, an NSRunLoop would probably be the right approach.