flutter-internationalization_skill

Overview

This skill is a complete guide for internationalizing Flutter apps using gen-l10n and the intl package. It shows how to configure code generation, create ARB message files, and wire localization into Material and Cupertino apps. The guide also covers number and date formatting, plural/select messages, locale overrides, and manual/custom strategies.

How this skill works

The skill explains two main approaches: gen-l10n (recommended) for automated ARB-based code generation, and the intl package for manual control. It walks through adding dependencies, creating l10n.yaml and ARB files, running flutter gen-l10n, and integrating generated delegates into MaterialApp. It also describes message types (placeholders, plurals, selects), formatting options, and advanced locale resolution and overrides.

When to use it

• Starting a new Flutter app that needs reliable localization with minimal boilerplate
• Translating an existing app to multiple languages and managing ARB files
• Formatting numbers, currency and dates according to user locales
• Supporting RTL languages and locale-specific layouts
• Implementing custom or legacy localization workflows with full control

Best practices

• Prefer gen-l10n for new projects to benefit from automated generation and safer APIs
• Add clear descriptions and placeholder metadata in ARB entries for translators
• Use placeholders and plural/select patterns instead of string concatenation
• Test every supported locale, including RTL layouts and edge-case formats
• Use format types for numbers/dates to ensure locale-aware rendering
• Keep messages short and reusable to simplify translation

Example use cases

• Add Spanish and English support using lib/l10n/app_en.arb and app_es.arb and run flutter gen-l10n
• Create parameterized greetings with placeholders and use AppLocalizations.of(context)!.greeting('Alice')
• Format currency and dates in messages using simpleCurrency or yMMMd patterns
• Temporarily force a locale for a widget with Localizations.override for previews or tests
• Implement a small app with a custom Map-based localization class for a lightweight footprint