private IEnumerator _sendScore(float score)
    {
#if SAVE_USERINFO
        string code = PlayerPrefs.GetString("user_code", null);
#else
        string code = userCode;
#endif
        if (string.IsNullOrEmpty(userCode))
        {
            code = _generateUserCode();
        }

        WWWForm form = new WWWForm();
        form.AddField("user_code", code);
#if SAVE_USERINFO
        form.AddField("name", PlayerPrefs.GetString("name"));
#else
        form.AddField("name", userName);
#endif
        form.AddField("score", score.ToString());
        using (WWW www = new WWW(SERVER_URL + API_ADDSCORE, form))
        {
            yield return(www);

            yield return(new WaitWhile(() => !www.isDone));

            if (!string.IsNullOrEmpty(www.error))
            {
                Debug.Log(www.error);
            }
            else
            {
                string res = www.text;
                if (!string.IsNullOrEmpty(res))
                {
                    rankingView.LoadData(_parseRankingJson(res));
                }
            }
        }
    }