WPF异步调用WCF服务

//1、创建一个异步对象，访问wcf
Func<string, string, List<NodeItem>> GetDataFromWCF = new Func<string, string, List<NodeItem>>(delegate(string _userCode, string _query)
{
　　　　　//此处写客户端调用WCF服务的代码
        return standardVideoTreeData.LoadData(_userCode, _query);
 });

//2、执行异步对象的异步方法 BeginInvoke 
IAsyncResult result = GetDataFromWCF.BeginInvoke(this.userCode, this.query, (res) =>
{
        List<NodeItem> tvsource = myFunc.EndInvoke(res);
　　　　　//3、更新客户端界面数据
        SetData(tvsource);
}, null);

 //更新客户端界面数据
 private void SetData(List<NodeItem> tvsource)
{
      this.Dispatcher.BeginInvoke(new Action(() =>
      {
              tree.ItemsSource = tvsource;
              loading_grid.Visibility = Visibility.Collapsed;
       }));
}