Other Uno.UI Features

Uno.UI.Toolkit is a set of extension methods or behaviors used to enhance WinUI and activate device/OS specific features.

Those methods are built to have no effect on a platform that does not support the enhanced feature: no need to wrap them into conditional code.

MenuFlyoutItem - Destructive style

iOS can display MenuFlyoutItem to warn user the action will be "destructive". In that case, the button text is displayed in red.

To set a MenuFlyoutItem as destructive, add the toolkit namespace to your XAML

xmlns:toolkit="using:Uno.UI.Toolkit"

And declare your MenuFlyoutItem as follow

<MenuFlyoutItem Text="Destructive action"
                toolkit:MenuFlyoutItemExtensions.IsDestructive="True" />

UICommand - Destructive style

iOS can display UICommand to warn user the action will be "destructive". In that case, the button text is displayed in red.

To set a UICommand as destructive, add the toolkit namespace to your code

using Uno.UI.Toolkit;

And declare your UICommand as follow

var uic = new UICommand("Destructive action");
uic.SetDestructive(true);

FromJson markup extension

FromJson lets you keep structured sample data in XAML without creating temporary view models. The extension takes a JSON payload, converts it to a dynamic object graph (ExpandoObject and nested dictionaries/lists), and assigns it to the consuming property.

The conversion follows simple rules so you always know what type a binding receives:

• JSON objects → ExpandoObject (access through IDictionary<string, object?>)
• JSON arrays → List<object?>
• JSON numbers → int (Int32) when the value fits, otherwise double
• JSON booleans → bool
• JSON strings → string
• JSON null → null

1. Store the JSON in an x:String resource so you can keep it formatted with xml:space="preserve".
2. Use the markup extension to deserialize the resource and set the DataContext, ItemsSource, or any other property that accepts an arbitrary object.

<Grid xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
      xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
      xmlns:uum="using:Uno.UI.Markup"
      xmlns:xml="http://www.w3.org/XML/1998/namespace">
    <Grid.Resources>
        <x:String x:Key="SampleData" xml:space="preserve">
{
    "Title": "Runtime Test",
    "Owner": { "Name": "Uno Platform" },
    "Numbers": [ 1, 2, 3 ]
}
        </x:String>
    </Grid.Resources>

    <TextBlock DataContext="{uum:FromJson Source={StaticResource SampleData}}"
               Text="{Binding Owner.Name}" />
</Grid>

You can also apply FromJson directly inside Page.DataContext, either by referencing an x:String resource or by using its content property to inline JSON:

<Page xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
      xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
      xmlns:uum="using:Uno.UI.Markup"
      xmlns:xml="http://www.w3.org/XML/1998/namespace">
    <Page.Resources>
        <x:String x:Key="SamplePerson" xml:space="preserve">
            {
                "Name": "Inline"
            }
        </x:String>
    </Page.Resources>

    <Page.DataContext>
        <uum:FromJson Source="{StaticResource SamplePerson}" />
    </Page.DataContext>

    <TextBlock Text="{Binding Name}" />
</Page>

<Page xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
      xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
      xmlns:uum="using:Uno.UI.Markup">
    <Page.DataContext>
        <uum:FromJson>
            <uum:FromJson.Source>
            {
                "Name": "Inline"
            }
            </uum:FromJson.Source>
        </uum:FromJson>
    </Page.DataContext>

    <TextBlock Text="{Binding Name}" />
</Page>

If the JSON string is empty or invalid, the extension throws a XamlParseException, allowing issues to surface early during page initialization.