ios中的延时执行

        [MBProgressHUDshowMessage:@"加载中"toView:self.view];

        dispatch_after(dispatch_time(DISPATCH_TIME_NOW, 1 * NSEC_PER_SEC), dispatch_get_main_queue(), ^{

            [MBProgressHUDshowError:@"暂无消息"toView:self.view];

        });