Xamarin表单ListView ItemsSource

Question

我试图在Xamarin Forms中使用ListView，我有一个List，我必须根据当天划分它

var activitiesServices = new ActivitiesServices();
        var activities = activitiesServices.GetActivities();

        var dataTemplate = new DataTemplate(typeof(TextCell));
        dataTemplate.SetBinding(TextCell.TextProperty, "Subject");

        var list = new ObservableCollection<Activity>();
        var list2 = new ObservableCollection<Activity>();
        var list3 = new ObservableCollection<Activity>();
        var list4 = new ObservableCollection<Activity>();
        var list5 = new ObservableCollection<Activity>();
        foreach (Activity item in activities) {
            var day = item.StartTime.DayOfWeek;
            switch ((int)day) {
                case 1:
                    list.Add(item);
                    break;
                case 2:
                    list2.Add(item);
                    break;
                case 3:
                    list3.Add(item);
                    break;
                case 4:
                    list4.Add(item);
                    break;
                case 5:
                    list5.Add(item);
                    break;
                default:
                    break;
            }}

直到这里顺利但是当我尝试填充主列表视图（在xaml中定义）时它会给我一个错误：

           if (list.Count != 0) {
            monday.ItemsSource = list;
            monday.ItemTemplate = dataTemplate;
        }
        if (list2.Count != 0) {
            tuesday.ItemsSource = list2;
            tuesday.ItemTemplate = dataTemplate;
        }
        if (list3.Count != 0) {
            wednesday.ItemsSource = list3;
            wednesday.ItemTemplate = dataTemplate;
        }
        if (list5.Count != 0) {
            friday.ItemsSource = list5;
            friday.ItemTemplate = dataTemplate;
        }
        if (list4.Count != 0) {
            thursday.ItemsSource = list4;
            thursday.ItemTemplate = dataTemplate;
        }

这是错误：System.NullReferenceException：对象引用未设置为对象的实例。

Answer 1

您可以尝试Syncfusion

提供的列表视图

在XAML中使用。这定义了组头模板

<syncfusion:SfListView x:Name="listView">
  <syncfusion:SfListView.GroupHeaderTemplate>
    <DataTemplate>
      <ViewCell>
        <ViewCell.View>
          <StackLayout BackgroundColor="#E4E4E4">
            <Label Text="{Binding Key}"
                   FontSize="22"
                   FontAttributes="Bold"
                   VerticalOptions="Center"
                   HorizontalOptions="Start"
                   Margin="20,0,0,0" />
          </StackLayout>
        </ViewCell.View>
      </ViewCell>
    </DataTemplate>
  </syncfusion:SfListView.GroupHeaderTemplate>
</syncfusion:SfListView>

它支持分组，似乎适合您的情况。