private IEnumerator RunGetAssetBundleCoroutine(string url, EventHnadlerHTTPAssetBundle assetBundleCallback, EventHandlerOnError errorCallback)
    {
        WWW www = new WWW(url);

        while (!www.isDone)
        {
            yield return(null);
        }

        if (string.IsNullOrEmpty(www.error))
        {
            if (assetBundleCallback != null)
            {
                assetBundleCallback(www.assetBundle, www.responseHeaders);
            }
            else
            {
                Debug.Log("<Color=#4f3c3c>no request callback method.</color>");
                yield return(null);
            }
        }
        else
        {
            if (errorCallback != null)
            {
                errorCallback(www.error);
            }
        }

        if (www != null)
        {
            www.Dispose();
            www = null;
        }
    }
 public void GetAssetBundle(string url, EventHnadlerHTTPAssetBundle assetBuntleCallback, EventHandlerOnError errorCallback)
 {
     StartCoroutine(RunGetAssetBundleCoroutine(url, assetBuntleCallback, errorCallback));
 }