Facebook Unity SDK Profile Pic Loading

using Facebook.MiniJSON;

FB.API (GetPictureURL(user["id"].ToString(), 128,128), Facebook.HttpMethod.GET, delegate(FBResult pictureResult)
{
    string imageUrl = DeserializePictureURLString(pictureResult.Text);
    StartCoroutine(LoadPictureEnumerator(imageUrl,pictureTexture =>
    {
        UserAvatar.sprite = Sprite.Create (pictureTexture, new Rect(0,0,128,128), new Vector2(0,0));
    }));
});

delegate void LoadPictureCallback (Texture2D texture);

IEnumerator LoadPictureEnumerator(string url, LoadPictureCallback callback)
{
    WWW www = new WWW(url);
    yield return www;
    callback(www.texture);
}

public string DeserializePictureURLString(string response)
{
    return DeserializePictureURLObject(Json.Deserialize(response));
}

public string DeserializePictureURLObject(object pictureObj)
{
    var picture = (Dictionary<string, object>)(((Dictionary<string, object>)pictureObj)["data"]);
    object urlH = null;
    if (picture.TryGetValue("url", out urlH))
    {
        return (string)urlH;
    }
    return null;
}

private string GetPictureURL(string facebookID, int? width = null, int? height = null, string type = null)
{
    string url = string.Format("/{0}/picture", facebookID);
    string query = width != null ? "&width=" + width.ToString() : "";
    query += height != null ? "&height=" + height.ToString() : "";
    query += type != null ? "&type=" + type : "";
    query += "&redirect=false";
    if (query != "") url += ("?g" + query);
    return url;
}