iPhone: Force UIButton to redraw itself

I g开发者_如何学Cot 5 UIButtons placed next to each other and what I wanna do is set image on first button, redraw it so it, wait for 1 second, then set some other image on second button, redraw second button and so on. I tried to set image on button, then call function sleep(1) and so on but it just freezes application for 5 seconds and then redraws all 5 buttons at the same time.

You can use performSelector:withObject:afterDelay: to delay the image changes.