是否有一种方法可以编写一个NSTimer，让它暂停程序一秒钟?

Trying to change a button pic, wait a second, then change back. Not having much luck trying to get that to work, so is there a way to just pause the program for a second, without having a timer actually executing anything, and without the program going on with the code?Trying to change a button pic, wait a second, t