public static void CreateLoader(string url, int version)
    {
        // Check if the asset in the loader table
        if (_loaders.ContainsKey(url))
        {
            WwwLoader existingLoader = _loaders[url].Value;
            existingLoader.AddRef();
        }


        // Create loader
        WwwLoader loader = new WwwLoader(url, version);

        loader.AddRef();

        // Add to existing loader
        _loaders.Add(url, _pendingLoaders.AddLast(loader));
    }
    /// <summary>
    /// Destroies the loader.
    /// </summary>
    /// <param name='loader'>
    /// Loader.
    /// </param>
    public static void DestroyLoader(WwwLoader loader)
    {
        if (loader == null)
        {
            return;
        }

        loader.ReleaseRef();

        if (loader.RefCount == 0)
        {
            Debug.Assert(_loaders.ContainsKey(loader.AssetPath), "Must exist");

            LinkedListNode <WwwLoader> loaderNode = _loaders[loader.AssetPath];
            _loaders.Remove(loader.AssetPath);
            loaderNode.List.Remove(loaderNode);
            loaderNode.Value.Destroy();
        }

        loader = null;
    }