private IEnumerator Download()
        {
            var downloader = _patcher.InternalDownloader;

            // 注册下载回调
            downloader.OnPatchFileCheckFailedCallback     = PatchEventDispatcher.SendWebFileCheckFailedMsg;
            downloader.OnPatchFileDownloadFailedCallback  = PatchEventDispatcher.SendWebFileDownloadFailedMsg;
            downloader.OnPatchFileDownloadSucceedCallback = PatchEventDispatcher.SendDownloadFilesProgressMsg;
            downloader.Download();
            yield return(downloader);

            // 检测下载结果
            if (downloader.DownloadStates != EDownloaderStates.Succeed)
            {
                yield break;
            }

            // 缓存本地资源版本号
            _patcher.CacheLocalResourceVersion();
            _patcher.SwitchNext();
        }