maui: SwipeView throw exception on windows

I just ran into the same problem with Visual Studio 17.4.5 and MAUI 7.0.59 in a demo project I’m developing for a conference where I’ll be talking about .NET MAUI and wanted to share my workaround.

I was able to get around the issue by migrating my XAML code to C# markup using the helper methods from the [.NET MAUI Community Toolkit] (https://learn.microsoft.com/de-de/dotnet/communitytoolkit/maui/markup/markup). Within the C# markup file, I was able to use conditional compilation to exclude the SwipeView on Windows.

See:

https://github.com/AndreKraemer/basta-2023-se-maui-demo/blob/fb33963810b7788795fcf6445d4d5f4cf256e26b/ConferenceMauiDemo/Views/SessionsPageMarkup.cs#L152

Since the SwipeView doesn’t work on Windows when using the application with a mouse, it wasn’t a big deal to exclude it from my view. To give Windows users the same functionality that users of other platforms have with the SwipeView, I added a context menu (right click). See: https://github.com/AndreKraemer/basta-2023-se-maui-demo/blob/fb33963810b7788795fcf6445d4d5f4cf256e26b/ConferenceMauiDemo/Views/SessionsPageMarkup.cs#L238

Since this was used to close at least #9540, #9423 and #8870 there seems to be a fair amount of interest. PR #11229 seems like it corrects this but says “The PR require some changes in the public API. Will maintain the changes up to date but need to wait to .NET 8.”

Fair enough, but if breaking changes are the problem at least put something in the community toolkit temporarily because waiting for .NET 8 to fix a bug in .NET 6 seems excessive.

I agree, I have a swipe view for use on mobile devices and am using context menus for desktop. At a minimum we need the presence of a swipe view in a collection view to at least not crash!

Absent a response from Microsoft I can only guess, but it looks like it’s being worked on. I noticed a while back that PR #11229 by @jsuarezruiz seems like it corrects this but says “The PR require some changes in the public API. Will maintain the changes up to date but need to wait to .NET 8.” That was in November of 2022, however it looks like a new decision has been reached and PR #11229 was closed at the beginning of July 2023 with “We are going to close this PR focusing on fix crashes or any problem that prevents the use of SwipeView in Windows while we continue to promote the implementations and accessibility on the desktop (keyboard support etc).”

A SwipeView without mouse support is not a very practical desktop UI element but as long as its presence does not crash the app (as it currently does in this example) it shouldn’t be too hard to code around that and offer an alternative desktop interface. Not hard, but tedious.

This issue still exists with Visual Studio 17.4.5 and MAUI 7.0.59.

How to reproduce:

1. Create a new MAUI project with .NET 7
2. Replace content of MainPage.xaml with

<?xml version="1.0" encoding="utf-8" ?>
<ContentPage xmlns="http://schemas.microsoft.com/dotnet/2021/maui"
             xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml"
             x:Class="MauiApp1.MainPage">

    <Grid RowDefinitions="Auto,*" Margin="10" RowSpacing="10">
        <Button Text="Insert items" Clicked="InsertItemsClicked" HorizontalOptions="Start"/>

        <CollectionView Grid.Row="1" ItemsSource="{Binding Items}">
            <CollectionView.ItemTemplate>
                <DataTemplate>
                    <SwipeView>
                        <Grid>
                            <Border Stroke="Blue" StrokeThickness="2">
                                <Label Text="{Binding}" Padding="5"/>
                            </Border>
                        </Grid>
                    </SwipeView>
                </DataTemplate>
            </CollectionView.ItemTemplate>
        </CollectionView>
    </Grid>
</ContentPage>

1. Replace content of MainPage.xaml.cs with

using System.Collections.ObjectModel;

namespace MauiApp1;

public partial class MainPage : ContentPage
{
    int counter = 1;

    public MainPage()
    {
        InitializeComponent();
        Items = new();
        BindingContext = this;
    }

    public ObservableCollection<string> Items { get; }

    private void InsertItemsClicked(object sender, EventArgs e)
    {
        const int numberOfEntries = 5;
        for (int i = 0; i < numberOfEntries; i++) { Items.Insert(0, $"Item {counter}"); counter++; }
    }
}

1. Press Insert items button until the items do not fit in the view anymore and would need a scrollbar -> Exception occurs. See screen cast:

Note: Remove the SwipeView from the DataTemplate. Then this error does not occur.

I’m seeing a similar issue in my simple MAUI application with an ObservableCollection<string> inside a CollectionView. I can add items, but once I remove an item and then try to add another item I get the UnhandledException: [Microsoft.UI.Xaml.UnhandledExceptionEventArgs] Exception = {"Value does not fall within the expected range."} Message = {"The parameter is incorrect."} I also have defensive code in each add/remove method to make sure the collection is not null and the item has content before removing or adding.