Xamarin加载CollectionView时出现无效强制转换，页面崩溃

我有一个CollectionView，原本要加载对象的所有属性，但打开页面时应用直接崩溃，崩溃发生在代码行View = (View)template.CreateContent();。已确认Libraries集合已正确填充数据，不存在空数据问题。

绑定方法代码 #

public void Bind(object itemBindingContext, ItemsView itemsView,
           Action<Size> reportMeasure = null, Size? size = null)
       {
           var template = _template.SelectDataTemplate(itemBindingContext, itemsView);

           var templateChanging = template != _selectedTemplate;

           if (templateChanging)
           {
               // Clean up any content we're still holding on to
               _itemContentView.Recycle();

               // Create the new content
               View = (View)template.CreateContent();

               // Set the binding context _before_ we create the renderer; that way, the bound data will be 
               // available during OnElementChanged
               View.BindingContext = itemBindingContext;

               // Make sure the Visual property is available when the renderer is created
               PropertyPropagationExtensions.PropagatePropertyChanged(null, View, itemsView);

               // Actually create the native renderer
               _itemContentView.RealizeContent(View);

               _selectedTemplate = template;
           }

           _itemContentView.HandleItemSizingStrategy(reportMeasure, size);

           if (!templateChanging)
           {
               // Same template, new data
               View.BindingContext = itemBindingContext;
           }

           itemsView.AddLogicalChild(View);
       }

CollectionView的XAML代码 #

<CollectionView VerticalScrollBarVisibility="Always"
                                Margin="0,10,20,0" 
                                ItemsSource="{Binding Libraries}"
                                VerticalOptions="StartAndExpand"
                                HeightRequest="210">
                        <CollectionView.ItemsLayout>
                            <LinearItemsLayout Orientation="Vertical"/>
                        </CollectionView.ItemsLayout>
                        <CollectionView.ItemTemplate>
                            <DataTemplate>
                            <ViewCell>
                                <Grid Margin="8,0">
                                    <Grid.RowDefinitions>
                                        <RowDefinition Height="*"/>
                                        <RowDefinition Height="auto"/>
                                    </Grid.RowDefinitions>
                                  <sh:Shadows Margin="0,0,0,5" 
                Shades="{sh:SingleShade Opacity=0.4, BlurRadius=10, Color=Black}"  CornerRadius="100">
                                        <Frame Grid.Column="0" BackgroundColor="#D9D9D9" HorizontalOptions="Center" VerticalOptions="Center" Padding="0" CornerRadius="100" WidthRequest="150" HeightRequest="150" IsClippedToBounds="True">
                                            <Image x:Name="userImage"  Source="{Binding Picture, Converter={StaticResource ByteArrayToImageConverter}}" WidthRequest="{OnPlatform iOS=100, Android=100}" HorizontalOptions="Center"/>
                                        </Frame>
                                    </sh:Shadows>
                                    <StackLayout Grid.Column="1" Margin="10,0,0,0">
                                        <Label Text="{Binding Name, TargetNullValue='Sconosciuto'}" FontFamily="Inter" FontAttributes="Bold" MaxLines="3" LineBreakMode="TailTruncation" FontSize="16" HorizontalOptions="Start" TextColor="Black" Margin="0,0,10,0"/>
                                        <Label Text="{Binding Address, TargetNullValue='Sconosciuto'}"  FontFamily="Inter" FontSize="13" HorizontalOptions="Start" TextColor="#D9D9D9"/>
                                    </StackLayout>
                                </Grid>
                                </ViewCell>
                            </DataTemplate>
                        </CollectionView.ItemTemplate>
                    </CollectionView>

ViewModel加载Libraries的代码 #

public LoanBookPageViewModel(Book book) {
            Book = book;
            Libraries = BookService.GetLibrariesWithAvailableBook(Book);
        }

可能的解决方向 #

• 移除ViewCell：CollectionView的ItemTemplate不需要包裹ViewCell（这是ListView的用法），直接将Grid作为DataTemplate的根元素。ViewCell会导致template.CreateContent()返回的不是View类型，强制转换失败引发崩溃。
• 检查模板选择逻辑：确认_template.SelectDataTemplate返回的DataTemplate有效，未返回null或非View类型的模板。
• 转换器异常处理：给ByteArrayToImageConverter添加空值判断和异常捕获逻辑，避免转换无效字节数组时抛出异常，导致模板创建过程崩溃。
• 异步加载数据：如果BookService.GetLibrariesWithAvailableBook是同步耗时操作，改成异步加载，加载完成后再更新Libraries集合，避免UI线程阻塞引发异常。

内容的提问来源于stack exchange，提问作者spoooooooonman