c# 在套接字中更新 ObservableCollection

Question

我需要在监听套接字时更新我的observableCollection。然后把myobservableCollection从大到小排序。我每次都在听任何更新。 这很好用。

但是当我向下滚动 longListSelector 时，**每次更新完成时，我都不能' 还没到尽头，它 returns 我到顶了。* * 如何更新它并能够向下滚动。

mySock.On("player:new-vote", (data) = > {
string newVoteData = data.ToString();
JObject obj = JObject.Parse(newVoteData);
string objId = (string) obj["id"];
int objStand = (int) obj["details"]["standing"];
int objUp = (int) obj["details"]["upVotes"];
int objDown = (int) obj["details"]["downVotes"];
string objBy = (string) obj["details"]["by"];
PlayerVotes newVote = new PlayerVotes() {
    by = objBy,
    _id = objId,
    downVotes = objDown,
    upVotes = objUp,
    standing = objStand
};
Deployment.Current.Dispatcher.BeginInvoke(() = > {
    var updateVoteSong = playerCollection.FirstOrDefault(x = > x._id == objId);
    updateVoteSong.votes = newVote;
    playerCollection = new ObservableCollection < PlayerSong > (playerCollection
        .OrderByDescending(x = > x.votes.standing));
    MainLongListSelector.ItemsSource = playerCollection;
});

});

Answer 1

首先，你不应该每次都覆盖你的 ObservableCollection，包含的数据会改变。

而是使用此扩展程序进行排序，例如：

public static class ObservableCollection
 {
      public static void Sort<TSource, TKey>(this ObservableCollection<TSource> source, Func<TSource, TKey> keySelector)
      {
          List<TSource> sortedList = source.OrderByDescending(keySelector).ToList();
          source.Clear();
          foreach (var sortedItem in sortedList)
          {
              source.Add(sortedItem);
          }
     }
 }

如果您每次都覆盖集合，绑定的控件可能会遇到严重的绑定问题，因为它们永远不会解除绑定。

要滚动到特定元素，您可以这样做：

var lastMessage = playerCollection.LastOrDefault();
MainLongListSelector.ScrollTo(lastMessage);

这可能不会给您 100% 合适的答案，但它应该会把您推向正确的方向

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