How do you do a foursquare style uitableview refresh?

If you haven't seen their imple开发者_运维百科mentation Of the refresh of a tableview it is extremely slick. I was surprised to see no search results asking for this to be explained so I figured ask it myself.

If you haven't seen it, it basically adds a subviews to the uitableview above the header to the blank part of the screen when you pull a uitableview view down farther than it has data to display. Sorry if that doesn't make sense but just download the app and you will immediately want to do it too.

Just wondering how they did it?

Here's a terrible video illustrating the concept:

http://nickthedude-neytq.posterous.com/

Here: http://www.drobnik.com/touch/2009/12/how-to-make-a-pull-to-reload-tableview-just-like-tweetie-2/ As you can see in (the title of) that post, this feature was actually 'invented' by Atebits and first used in Tweetie 2, and Foursquare is just one of the many apps that copied this functionality.

Tweetie 2 was just recently bought by Twitter by the way, so if you're looking for that app, it's now called 'Twitter for iPhone'.