public void OnMediaSaveCompleted(string message)
 {
     if (callback != null)
     {
         callback(null);
         callback = null;
     }
 }
        public void OnMediaSaveFailed(string error)
        {
            if (string.IsNullOrEmpty(error))
            {
                error = "Unknown error";
            }

            if (callback != null)
            {
                callback(error);
                callback = null;
            }
        }
        public static void Initialize(NativePhoto.MediaSaveCallback callback)
        {
            if (instance == null)
            {
                instance = new GameObject("GalleryMediaSave").AddComponent <GalleryMediaSave>();
                DontDestroyOnLoad(instance.gameObject);
            }
            else if (instance.callback != null)
            {
                instance.callback(null);
            }

            instance.callback = callback;
        }