Assetbundle fail to load at IOS local

Hi

I'm encounter with some assetbundle problem on IOS device

I can download my assetbundle file from internet and save it at some local path

but when I try to load it, it just crash and the App will shut down automatically.

That's something will not happen in Android

This also won't happen when I preview in Unity( works fine on Mac and PC).

here's my ccode :




IEnumerator DownloadBundle()
{
while (!Caching.ready)
yield return null;
www = WWW.LoadFromCacheOrDownload(downloadPath, 1);
yield return www;
isDownloading = false;

AssetBundle bundle = www.assetBundle;
AssetBundleRequest request = bundle.LoadAssetAsync("Car", typeof(GameObject));
yield return request;

GameObject obj = request.asset as GameObject;

bundle.Unload(false);
www.Dispose();

Instantiate(obj, transform.position, transform.rotation);
}

Is there anything that I do wrong?