.NET MAUI – One or more invalid file names were detected.

Developers working on .NET MAUI projects may encounter a perplexing error during the build process, revealing invalid file names that must adhere to specific rules.

/usr/local/share/dotnet/packs/Microsoft.Maui.Resizetizer.Sdk/7.0.101/targets/Microsoft.Maui.Resizetizer.targets(525,9): error : One or more invalid file names were detected. File names must be lowercase, start and end with a letter character, and contain only alphanumeric characters orunderscores.

The Solution

To resolve this issue, developers need to identify and correct the problematic file names. On macOS, the hidden file .DS_Store is a common culprit causing this error. Here’s a step-by-step guide to resolving the issue:

For macOS

  1. Open Finder.
  2. Navigate to the root directory of your project.
  3. Press Command + Shift + Period to toggle the visibility of hidden files.
  4. Look for any hidden files, particularly .DS_Store.
  5. Delete or rename the problematic hidden files.

If the Finder app does not show any files, try opening a terminal, navigate to the resources folder of your project, and type ls -la to see the files. It should display the invalid files. Remove them accordingly.

For Windows

  1. Open File Explorer.
  2. Navigate to the root directory of your project.
  3. Select the “View” tab on the File Explorer ribbon.
  4. Check the “Hidden items” option in the “Show/hide” group.
  5. Look for any hidden files, and particularly check for files similar to .DS_Store (Windows might have different hidden files causing the issue).
  6. Delete or rename the problematic hidden files.
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.NET MAUI Android Error: Type androidx.collection.ArrayMapKit is defined multiple times

One common challenge is AndroidX dependency conflicts. In this blog post, we’ll guide you through resolving compilation errors related to AndroidX in .NET MAUI. Before we proceed, let’s take a look at the error message that may have troubled you:

/Users/Username/Documents/src/ProjectFolder/Project: Error JAVA0000: Error in /Users/Username/.nuget/packages/xamarin.androidx.collection.jvm/1.3.0.1/buildTransitive/net6.0-android31.0/../../jar/androidx.collection.collection-jvm.jar:androidx/collection/ArrayMapKt.class:
Type androidx.collection.ArrayMapKt is defined multiple times: /Users/Username/.nuget/packages/xamarin.androidx.collection.jvm/1.3.0.1/buildTransitive/net6.0-android31.0/../../jar/androidx.collection.collection-jvm.jar:androidx/collection/ArrayMapKt.class, /Users/Username/.nuget/packages/xamarin.androidx.collection.ktx/1.2.0.5/buildTransitive/net6.0-android31.0/../../jar/androidx.collection.collection-ktx.jar:androidx/collection/ArrayMapKt.class
Compilation failed
java.lang.RuntimeException: com.android.tools.r8.CompilationFailedException: Compilation failed to complete, origin: /Users/Username/.nuget/packages/xamarin.androidx.collection.jvm/1.3.0.1/buildTransitive/net6.0-android31.0/../../jar/androidx.collection.collection-jvm.jar
androidx/collection/ArrayMapKt.class

In my case the meaning of this error message is: Type androidx.collection.ArrayMapKt is defined multiple times

Examine Dependencies and Manually Delete bin and obj Folders:

Start by inspecting your project’s dependencies. Ensure that you have the same versions of .NET MAUI packages and other libraries. Dependency mismatches can often lead to compilation errors.

Sometimes, cleaning your project isn’t enough.
To ensure a fresh build, you might need to manually delete the bin and obj folders. You can find these folders in your project directory. They contain build artifacts and removing them helps clear cached data.

Verify NuGet Packages:

Review your NuGet packages. Look out for multiple versions of the same library, as this can lead to conflicts. If you find any conflicting packages, remove the outdated or conflicting versions. You may need to edit your project’s .csproj file to resolve these package issues.

Additionally, if you’ve recently installed a new NuGet package with has an Android dependency, make sure you have the correct version. A different version might introduce incompatibilities with the already installed pacakages.

This content has 7 months. Some of the information in this post may be out of date or no longer work. Please, read this page keeping its age in your mind.

.NET MAUI: iOS ListView disappearing cells

In this article, we will delve into a persistent .NET MAUI issue affecting ListViews on the iOS platform in .NET 7 builds. While the .NET 8 preview has addressed this issue, developers seeking a solution can employ the BindableLayout as a temporary workaround. We’ll also explore the concept of BindableLayout and touch on the CachingStrategy within ListViews.

The Problem: Disappearing Cells in ListViews on iOS

The issue at hand revolves around the behavior of ListViews on the iOS platform in .NET 7 builds. As users scroll through the list elements, the ListView cells mysteriously disappear, causing a jarring experience. While the .NET 8 preview has resolved this vexing problem, the official release is still pending, leaving developers seeking immediate solutions.

The Workaround: BindableLayout within ScrollView

A viable workaround to mitigate the disappearing cell issue involves utilizing the BindableLayout within a ScrollView. The BindableLayout.ItemSource property can be harnessed to mimic the ListView’s behavior. However, it’s crucial to acknowledge that this solution might not deliver the same performance as a native ListView.

Example Code

Here’s how you can implement the BindableLayout workaround:

<ScrollView>
    <StackLayout>
        <BindableLayout.ItemsSource>
            <x:Array Type="{x:Type local:ItemModel}">
                <local:ItemModel Name="Item 1" />
                <local:ItemModel Name="Item 2" />
                <local:ItemModel Name="Item 3" />
                <!-- Add more items here -->
            </x:Array>
        </BindableLayout.ItemsSource>
        <BindableLayout.ItemTemplate>
            <DataTemplate>
                <Label Text="{Binding Name}" />
            </DataTemplate>
        </BindableLayout.ItemTemplate>
    </StackLayout>
</ScrollView>

BindableLayout: A Glimpse

BindableLayout is a versatile feature within the .NET MAUI framework that allows developers to easily bind collections to layout controls. It’s an excellent alternative when dealing with scenarios where a native ListView isn’t performing optimally or in cases like the aforementioned issue. BindableLayout empowers developers to achieve the desired UI layout while maintaining data synchronization.

Use BindableLayout when you want more control over the layout of your items, need to create a dynamic UI with varying layouts, and don’t necessarily require built-in performance optimizations.

Understanding CachingStrategy within ListViews

ListViews in .NET MAUI come with a property known as CachingStrategy. This property determines how the ListView should cache its visual elements, significantly influencing performance. There are three options:

  1. RecycleElement: This strategy reuses existing cells, enhancing memory usage and rendering speed. However, it might pose issues when complex cell layouts are used.
  2. RetainElement: This strategy preserves cells for the duration of the ListView’s existence. While memory consumption can be higher, it can be useful for more intricate cell layouts.
  3. None: In this strategy, no caching is employed, causing cells to be created and destroyed frequently. While it minimizes memory usage, it can have an adverse impact on performance.

Conclusion

While the .NET MAUI framework continues to evolve, issues like the disappearing ListView cells on iOS in .NET 7 builds are inevitable. Developers eagerly anticipate the benefits that .NET 8 will bring, including the resolution of this particular problem. In the interim, the BindableLayout within a ScrollView offers a workaround that replicates the ListView’s behavior, albeit with potential performance differences. By understanding concepts like BindableLayout and the CachingStrategy within ListViews, developers can navigate these challenges while continuing to create engaging and efficient cross-platform applications. Stay tuned for the official .NET 8 release and more innovations that will undoubtedly enhance the .NET MAUI experience.

https://github.com/dotnet/maui/issues/11640

This content has 10 months. Some of the information in this post may be out of date or no longer work. Please, read this page keeping its age in your mind.

.NET MAUI: Label issue, Overflowing Texts in StackLayouts

In this blog post, we will explore a known issue affecting the Label UserControl in .NET MAUI when used within a StackLayout. We will explain how this problem manifests and the temporary solution proposed by the Microsoft team.

The Issue


The problem arises when using the Label UserControl inside a StackLayout UserControl. Despite setting the parent UserControl’s width and height, the Label does not respect these dimensions and overflows its content. This can lead to visual glitches and unintended behavior in the application’s user interface.

Reproducing the Issue


To replicate the issue, follow these steps:

  1. Add a Grid with a column width of *
  2. Add a StackLayout as the only child of the Grid
  3. Add a background color to the StackLayout for better visibility of the issue
  4. Add a Label with content that exceeds the available width and can’t fit on a single line.

For example

<Grid>
    <Grid.ColumnDefinitions>
        <ColumnDefinition Width="*" />
    </Grid.ColumnDefinitions>

    <StackLayout BackgroundColor="LightGray">
        <Label Text="This is a very long text that will overflow the StackLayout width." />
    </StackLayout>
</Grid>

The Proposed Solution


While the Microsoft team is actively working on addressing this issue, a temporary solution is available to mitigate the problem. By setting the IsClippedToBounds parameter of the StackLayout to true, we can prevent the Label from overflowing its parent’s boundaries.

What does IsClippedToBounds do?


IsClippedToBounds is a property of the StackLayout that determines whether its children should be clipped to fit within the bounds of the parent container. When this property is set to true, any content that extends beyond the StackLayout’s boundaries will be clipped and hidden, ensuring that it does not visually overflow the container.

A tiny disadvantage

While setting the IsClippedToBounds property can help mitigate the issue of overflowing content in a StackLayout, it comes with its own set of limitations. One significant drawback is that it restricts the control from growing both horizontally and vertically within the parent container.

Implementation of the Temporary Solution


To apply the temporary solution to our issue, we simply need to add the IsClippedToBounds="True" attribute to the StackLayout:

<Grid>
    <Grid.ColumnDefinitions>
        <ColumnDefinition Width="*" />
    </Grid.ColumnDefinitions>

    <StackLayout BackgroundColor="LightGray" IsClippedToBounds="True">
        <Label Text="This is a very long text that will overflow the StackLayout width." />
    </StackLayout>
</Grid>

Conclusion


The .NET MAUI Label UserControl issue affecting StackLayout is an acknowledged problem by the Microsoft team. While a permanent fix is being developed, we can use the IsClippedToBounds property as a temporary solution to prevent the Label from overflowing its parent’s boundaries. Keep an eye on future updates from Microsoft to stay informed about the resolution of this issue and any other improvements they bring to the .NET MAUI framework. Happy coding!

https://github.com/dotnet/maui/issues/12895

This content has 10 months. Some of the information in this post may be out of date or no longer work. Please, read this page keeping its age in your mind.