private async void UpdateDeviceList()
        {
            ObservableCollection <DeviceInfo> list = await ServerApi.GetDeviceList();

            if (list != null)
            {
                deviceList.ItemsSource = list;

                ICollectionView dataView = CollectionViewSource.GetDefaultView(deviceList.ItemsSource); //获取数据源视图
                dataView.SortDescriptions.Clear();                                                      //清空默认排序描述
                SortDescription sd = new SortDescription("alive", ListSortDirection.Descending);
                dataView.SortDescriptions.Add(sd);                                                      //加入新的排序描述
                dataView.Refresh();
            }
        }