stop execution of process for milliseconds

I'm creating a Tic tac toe game, in that 开发者_Go百科after click made by user automatically the cpu will respond. I want the cpu response after 0.50 seconds, the sleep() function takes too many time, I don't want that much time, is there any other way to do so?

use

[self performSelector:@selector(FunctionName) withObject:nil afterDelay:0.5 ];

usleep(500000)

use sleep property and give (more milliseconds)