listview - Xamarin 表单 ListView 组标题模板不起作用

Question

我正在尝试在 xamarin 表单中使用组 header 模板 我已按照以下文章实现，但没有成功 http://motzcod.es/post/94643411707/enhancing-xamarinforms-listview-with-grouping 甚至从这里接受了建议 http://www.infinite-x.net/2015/04/08/working-with-the-listview-groupheadertemplate/

如果我放置 GroupDisplayBinding，即使我有模板，我也会得到正常的样式

<ListView.GroupHeaderTemplate>
        <ViewCell>
            <StackLayout
              VerticalOptions="FillAndExpand"
              BackgroundColor="#009688">
              <Label  Text="{Binding Key}"  TextColor="White" Margin="10" FontSize="Medium" />
            </StackLayout>
        </ViewCell>
      </ListView.GroupHeaderTemplate>

如果我删除 GroupDisplayBinding，我将在组中获得我的组类类型，如下图所示

采集代码

private ObservableCollection<Grouping<string, MFullIssue>> _Issues;
        public ObservableCollection<Grouping<string, MFullIssue>> Issues
        {
            get { return _Issues; }
            set { _Issues = value; OnPropertyChanged(); }
        }

 SthotramService.service.Issues().ContinueWith((t) =>
            {
                var sorted = from c in t.Result
                             orderby c.IssueTypeName
                             group c by c.IssueTypeName
                             into theGroup
                             select new Grouping<string, MFullIssue>(theGroup.Key, theGroup);

                Issues = new ObservableCollection<Grouping<string, MFullIssue>>(sorted);
            });

集合对象

public class MFullIssue
    {
        public int IssueID { get; set; }
        public int IssueTypeID { get; set; }
        public string Issue { get; set; }
        public int DisplayOrder { get; set; }
        public bool IsActive { get; set; }
        public string IssueTypeName { get; set; }
        public string IssueTypeDesc { get; set; }
        public List<MResolution> Resolutions { get; set; }
    }

分组类

public class Grouping<K,T>:ObservableCollection<T>
    {
        public K Key { get; private set; }

        public Grouping(K key, IEnumerable<T> items)
        {
            Key = key;
            foreach (var item in items)
            {
                Items.Add(item);
            }
        }
    }

Answer 1

查看我的 Grouped ListView 代码，您的 GroupHeaderTemplate 需要是 DataTemplate。不确定这是否是根本问题，但如果不是，以后肯定会导致问题:

<ListView.GroupHeaderTemplate>
    <DataTemplate>
        <ViewCell>
            ...

除此之外，我没有发现您的代码有任何问题，因此您可能需要确保 ObservableCollection 中的组看起来正确。