mbprogresshud简单使用

 [MBProgressHUD showMessage:@"我在后台等你==||"];
            
            dispatch_after(dispatch_time(DISPATCH_TIME_NOW, (int64_t)(3.0 * NSEC_PER_SEC)), dispatch_get_main_queue(), ^{
                 exit(0);
                // 移除HUD
                [MBProgressHUD hideHUD];
                
                // 提醒有没有新数据
                //[MBProgressHUD showError:@"没有新数据"];
            });