+ (void)verificationCode:(void(^)())blockYes blockNo:(void(^)(id time))blockNo {

    __block int timeout=; //倒计时时间

    dispatch_queue_t queue = dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, );

    dispatch_source_t _timer = dispatch_source_create(DISPATCH_SOURCE_TYPE_TIMER, , ,queue);

    dispatch_source_set_timer(_timer,dispatch_walltime(NULL, ),1.0*NSEC_PER_SEC, ); //每秒执行

    dispatch_source_set_event_handler(_timer, ^{

        if(timeout<=){ //倒计时结束，关闭

            dispatch_source_cancel(_timer);

            dispatch_async(dispatch_get_main_queue(), ^{

                //设置界面的按钮显示 根据自己需求设置

                blockYes();

            });

        }else{

            //            int minutes = timeout / 60;

            int seconds = timeout % ;

            NSString *strTime = [NSString stringWithFormat:@"%.2d", seconds];

            dispatch_async(dispatch_get_main_queue(), ^{

                //设置界面的按钮显示 根据自己需求设置

                NSLog(@"____%@",strTime);

                blockNo(strTime);

            });

            timeout--;

        }

    });

    dispatch_resume(_timer);

}