/// <summary>
 /// 释放这个AB包里的单个资源
 /// </summary>
 public void UnloadAsset(string bundleName, string assetName)
 {
     if (resObj.ContainsKey(bundleName))
     {
         AssetResObj tmpAsset = resObj[bundleName];
         tmpAsset.UnloadAsset(assetName);
     }
 }
    /// <summary>
    /// 释放这个AB包里的所有资源
    /// </summary>
    /// <param name="bundleName"></param>
    public void UnloadAsset(string bundleName)
    {
        if (resObj.ContainsKey(bundleName))
        {
            AssetResObj tmpAsset = resObj[bundleName];
            tmpAsset.UnloadAsset();
        }

        Resources.UnloadUnusedAssets();
    }