Unity 协程等待某个条件完成

1. 使用 WaitUntil ，如下图所示：

protected virtual IEnumerator UpdateConfig()
    {
        configJsonStr = "";
        using UnityWebRequest request = UnityWebRequest.Get(configJsonUri);
        UnityWebRequestAsyncOperation operation = request.SendWebRequest();
        yield return new WaitUntil(() => { return operation.isDone; });
        try
        {
            switch (request.result)
            {
                case UnityWebRequest.Result.Success:
                    configJsonStr = request.downloadHandler.text;
                    Debug.LogFormat("【获取配置文件】成功：fileUri={0} fileStr=\r\n{1}", configJsonUri, configJsonStr);
                    break;
                case UnityWebRequest.Result.InProgress:
                    break;
                default:
                    Debug.LogErrorFormat("【获取配置文件】失败：fileUri={0} errMsg={1}", configJsonUri, request.error);
                    break;
            }
        }
        catch (Exception ex)
        {
            Debug.LogException(ex);
        }
    }

2. 参考文档
　　https://docs.unity.cn/cn/current/ScriptReference/WaitUntil.html