Spell Checking

Uno Platform provides optional spell-checking support for TextBox controls on all Skia-based targets. When enabled, misspelled words are underlined in red and opening the context menu (secondary click or long-press) on a misspelled word presents spelling suggestions.

Enabling Spell Checking

Spell-checking is provided by the Uno.WinUI.SpellChecking package. To include it, add the SpellChecking feature to your project's UnoFeatures:

<UnoFeatures>
    SpellChecking;
    <!-- other features -->
</UnoFeatures>

Once enabled, any TextBox with IsSpellCheckEnabled="True" (the default) will display spell-checking visuals. An English (en_US) dictionary is included by default.

Custom Dictionaries

The default dictionary is English (en_US). To add spell-checking for other languages, load Hunspell-compatible dictionary files (.dic and .aff) at application startup using FeatureConfiguration.TextBox.CustomSpellCheckDictionaries.

Obtaining Dictionaries

Hunspell-compatible dictionaries are freely available from:

• LibreOffice dictionaries — covers 100+ languages
• Hunspell project on GitHub

Download the .dic and .aff files for your target language and include them in your project as embedded resources.

Loading a Custom Dictionary

1. Add the dictionary files to your project and set their Build Action to Embedded Resource.

2. Load the dictionaries at application startup (e.g., in App.xaml.cs):

using Uno.UI;

// Load a French dictionary from embedded resources
var assembly = typeof(App).Assembly;
var frDic = assembly.GetManifestResourceStream("MyApp.Dictionaries.fr_FR.dic");
var frAff = assembly.GetManifestResourceStream("MyApp.Dictionaries.fr_FR.aff");

FeatureConfiguration.TextBox.CustomSpellCheckDictionaries = new()
{
    (frDic!, frAff!)
};

Multiple dictionaries can be loaded simultaneously. The spell-checker validates words against all loaded dictionaries — a word is considered correct if it is found in any dictionary:

FeatureConfiguration.TextBox.CustomSpellCheckDictionaries = new()
{
    (frDic!, frAff!),
    (deDic!, deAff!)
};