public void OnCampaignListener_OnMissionCompleted(string param)
        {
            string[] callbackData = Regex.Split(param, DELIMITER);

            if (callbackData.Length > 0)
            {
                List <string> rewardIds = new List <string>(callbackData);

                if (listener != null)
                {
                    listener.OnMissionComplete(rewardIds);
                }
            }
        }