1、可以使用：

- (void) timeEnough

{

 UIButton *btn=(UIButton*)[self.view viewWithTag:33];

 btn.selected=NO; 

[timer invalidate];

 timer=nil; 

}

 - (void) btnDone:(UIButton*)btn

 {

 if(btn.selected) return;

 btn.selected=YES;

 [self performSelector:@selector(timeEnough) withObject:nil afterDelay:3.0]; 

//to do something.

｝

2、個人覺得這種方法更為好用些。

- (void)todoSomething:(id)sender

{

    //在這裡做按鈕的想做的事情。

}

- (void)starButtonClicked:(id)sender

{

    //先將未到時間執行前的任務取消。

    [[selfclass] cancelPreviousPerformRequestsWithTarget:selfselector:@selector(todoSomething:) object:sender];

    [self performSelector

}