C#判断useragent是pc还是手机端

public static bool CheckAgent(string userAgent)
        {
            bool flag = false;
            string[] keywords = { "Android", "iPhone", "iPod", "iPad", "Windows Phone", "MQQBrowser"};
            //排除 Windows 桌面系统
            if (!userAgent.Contains("Windows NT") || (userAgent.Contains("Windows NT") && userAgent.Contains("compatible; MSIE 9.0;")))
            {
                //排除 苹果桌面系统
                if (!userAgent.Contains("Windows NT") && !userAgent.Contains("Macintosh"))
                {
                    foreach (string item in keywords)
                    {
                        if (userAgent.Contains(item))
                        {
                            flag = true;
                            break;
                        }
                    }
                }
                flag = true;
            }
            return flag;
        }