根据秒数倒计时剩余时分秒

- (void)getNumBtnActionWithTimeout:(NSInteger)timeout{
    
    __block NSInteger totalSecond = timeout;
    //全局队列    默认优先级
    dispatch_queue_t quene = dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0);
    //定时器模式  事件源
    dispatch_source_t timer = dispatch_source_create(DISPATCH_SOURCE_TYPE_TIMER, 0, 0, quene);
    //NSEC_PER_SEC是秒，＊1是每秒
    dispatch_source_set_timer(timer, dispatch_walltime(NULL, 0), NSEC_PER_SEC * 1, 0);
    //设置响应dispatch源事件的block，在dispatch源指定的队列上运行
    dispatch_source_set_event_handler(timer, ^{
        //回调主线程，在主线程中操作UI
        
        if (totalSecond > 0) {
            
            int hours = (int)(totalSecond/3600);
            int minute = (int)(totalSecond-hours*3600)/60;
            int second = (int)totalSecond-hours*3600-minute*60;
            dispatch_sync(dispatch_get_main_queue(), ^{
                _probationLabel.text = [NSString stringWithFormat:@"%d : %d : %d",hours,minute,second];
            });
            
            totalSecond--;
        }
        else
        {
            //这句话必须写否则会出问题
            dispatch_source_cancel(timer);
            
        }
        ;
    });
    //启动源
    dispatch_resume(timer);
}