.NET MAUI应用iOS端导航至部分页面时抛出UITableView错误

我开发的跨Android/iOS的MAUI应用，在iOS设备（模拟器或真机）导航至StocktakingView页面时，会抛出UITableView相关错误（截图如下）：

已知数据在跳转前已通过HTTP请求加载完成，通过导航参数传递到目标页面，且其他使用相同逻辑的含CollectionView页面无此问题。已尝试的修复手段包括：将CollectionView放入Grid、替换为ListView、移除CollectionView、移除OnAppearing事件，但均未解决。

开发环境：Windows Visual Studio 17.9.2，连接安装XCode 15.2的Mac，使用Community MVVM Toolkit。

相关代码片段 #

StocktakingView的XAML代码 #

<ContentPage xmlns=...>
<ContentPage.Behaviors>
    <toolkit:EventToCommandBehavior EventName="Appearing" Command="{Binding AppearingCommand}" />
    <toolkit:EventToCommandBehavior EventName="NavigatedFrom" Command="{Binding NavigatedFromCommand}" />
</ContentPage.Behaviors>
<ContentPage.ToolbarItems>
    <ToolbarItem Command="{Binding CreateCommand}" IconImageSource="{FontImageSource FontFamily=MaterialSharp, Glyph={x:Static m:MaterialSharp.Add}, Color={AppThemeBinding Dark=White, Light=Black}}" />
</ContentPage.ToolbarItems>
    <CollectionView ItemsSource="{Binding Stocktakings}">
        <CollectionView.ItemTemplate>
            <DataTemplate x:DataType="model:Stocktaking">
                <Grid ColumnDefinitions="*,*" Padding="10">
                    <Grid.GestureRecognizers>
                        <TapGestureRecognizer Command="{Binding Source={RelativeSource AncestorType={x:Type vm:StocktakingViewModel}}, Path=TapCommand}" CommandParameter="{Binding .}" />
                    </Grid.GestureRecognizers>
                    <Label Grid.Column="0" Text="{Binding Name}" FontAttributes="Bold" />
                    <Label Grid.Column="1" Text="{Binding Status}" />
                </Grid>
            </DataTemplate>
        </CollectionView.ItemTemplate>
    </CollectionView>
</ContentPage>

StocktakingViewModel代码 #

[QueryProperty("Stocktakings_list", "stocktakings")]
public partial class StocktakingViewModel : BaseViewModel
{
    private readonly IUserDialogs _userDialogs;
    private readonly IGenericService<Stocktaking, StocktakingCreationInfo> _stocktakingService;

    [ObservableProperty]
    List<Stocktaking> stocktakings_list;

    [ObservableProperty]
    ObservableCollection<Stocktaking> stocktakings;

    public StocktakingViewModel(IUserDialogs userDialogs, IGenericService<Stocktaking, StocktakingCreationInfo> stocktakingService)
    {
        _userDialogs = userDialogs;
        _stocktakingService = stocktakingService;
    }

    [RelayCommand]
    private void OnAppearing()
    {
        Stocktakings = new ObservableCollection<Stocktaking>(Stocktakings_list);
    }
...

导航跳转代码 #

private async Task NavigateToStocktaking()
{
    List<Stocktaking> stocktakings = await _stocktakingService.GetAll();

    Dictionary<string, object> param = new Dictionary<string, object>
    {
        { "stocktakings", stocktakings }
    };

    await Shell.Current.GoToAsync(nameof(StocktakingView), param);
}

可能的解决方向 #

1. 移除Appearing事件依赖，改用属性变更触发集合初始化
   iOS上CollectionView的渲染时机与Android存在差异，Appearing事件触发时视图可能尚未完成初始化。可以直接在Stocktakings_list属性变更时初始化绑定集合：

[ObservableProperty]
List<Stocktaking> stocktakings_list;

// 重写属性变更回调
partial void OnStocktakings_listChanged(List<Stocktaking> value)
{
    if (value != null)
    {
        Stocktakings = new ObservableCollection<Stocktaking>(value);
    }
}

同时删除OnAppearing命令中的集合初始化代码，让数据参数传递完成后自动更新UI绑定。

2. 强制在UI线程执行集合更新操作
   iOS对UI操作的线程要求严格，即使数据提前加载，集合初始化操作也可能意外跑在非UI线程。用MainThread包裹操作确保在UI线程执行：

[RelayCommand]
private void OnAppearing()
{
    if (Stocktakings_list != null)
    {
        MainThread.BeginInvokeOnMainThread(() =>
        {
            Stocktakings = new ObservableCollection<Stocktaking>(Stocktakings_list);
        });
    }
}

3. 明确CollectionView的布局约束
   给CollectionView添加明确的布局属性，避免iOS上因布局异常导致UITableView渲染错误：

<ContentPage.Content>
    <CollectionView ItemsSource="{Binding Stocktakings}" VerticalOptions="FillAndExpand">
        <!-- 现有ItemTemplate代码 -->
    </CollectionView>
</ContentPage.Content>

4. 校验导航参数传递完整性
   在ViewModel的OnStocktakings_listChanged回调中添加日志，确认Stocktakings_list是否被正确赋值，排除参数传递过程中数据丢失或为空的情况。

内容的提问来源于stack exchange，提问作者Fryndorfer