maui-collectionview（毛伊岛收藏视图）

CollectionView –.NET MAUI

Use CollectionView for displaying scrollable lists and grids of data. It replaces ListView and offers better performance, flexible layouts, and no ViewCell requirement.

Essential patterns

Basic setup

<CollectionView ItemsSource="{Binding Items}">
    <CollectionView.ItemTemplate>
        <DataTemplate x:DataType="models:Item">
            <HorizontalStackLayout Padding="8" Spacing="8">
                <Image Source="{Binding Icon}" WidthRequest="40" HeightRequest="40" />
                <Label Text="{Binding Name}" VerticalOptions="Center" />
            </HorizontalStackLayout>
        </DataTemplate>
    </CollectionView.ItemTemplate>
</CollectionView>

• Bind ItemsSource to an ObservableCollection<T> so the UI updates on add/remove.
• Each item template root must be a Layout or View — never use ViewCell.
• Always set x:DataType on DataTemplate for compiled bindings.

SwipeView — binding from inside DataTemplate

Commands inside a DataTemplate can't directly reach your ViewModel. Use RelativeSource AncestorType:

<SwipeItem Text="Delete"
           BackgroundColor="Red"
           Command="{Binding Source={RelativeSource AncestorType={x:Type viewmodels:MainViewModel}}, Path=DeleteCommand}"
           CommandParameter="{Binding}" />

Pull-to-refresh

Wrap CollectionView in a RefreshView. Set IsRefreshing back to false when done:

<RefreshView IsRefreshing="{Binding IsRefreshing}"
             Command="{Binding RefreshCommand}">
    <CollectionView ItemsSource="{Binding Items}" />
</RefreshView>

Incremental loading (infinite scroll)

<CollectionView ItemsSource="{Binding Items}"
                RemainingItemsThreshold="5"
                RemainingItemsThresholdReachedCommand="{Binding LoadMoreCommand}" />

⚠️ Do NOT use with StackLayout-based ItemsLayout — it has no virtualization and triggers infinite threshold-reached events. Always use LinearItemsLayout or GridItemsLayout.

Performance tips

• Use MeasureFirstItem for uniform item sizes — significantly faster than the default MeasureAllItems: <LinearItemsLayout Orientation="Vertical" ItemSizingStrategy="MeasureFirstItem" />
• Always use ObservableCollection<T>, not List<T>. Swapping a List forces a full re-render.
• Update collections on the UI thread — MainThread.BeginInvokeOnMainThread(() => Items.Add(item)).

Common gotchas