iiEsaywebUIapp/docs/localization.md

Localization (i18n)

• Supported locales: en, de, fr, it.
• Uses Flutter's gen_l10n with ARB files and the intl package for date/number formatting.

Install & Generate

• Install packages:
  • flutter_localizations (Flutter SDK)
  • intl: ^0.20.2
• Files are under lib/l10n/*.arb. The template is app_en.arb.
• Generate localizations:
  • flutter gen-l10n
  • or run a full build: flutter pub get && flutter gen-l10n

Usage Examples

• Basic text:
  • Text(AppLocalizations.of(context)!.appTitle)
• With placeholder:
  • Text(AppLocalizations.of(context)!.dynamicContentWithPlaceholder('Alex'))
• Pluralization:
  • Text(AppLocalizations.of(context)!.itemsCount(3))
• Date/time formatting:
  • final dateText = DateFormat.yMMMMEEEEd(Localizations.localeOf(context).toString()).format(DateTime.now());
  • Text(dateText)
• Number formatting:
  • final price = NumberFormat.currency(locale: Localizations.localeOf(context).toString(), symbol: '€').format(1234.56);
  • Text(price)

Add a New Language

• Create a new ARB file in lib/l10n/, e.g. app_es.arb.
• Copy keys from app_en.arb and provide translated values.
• Ensure placeholders and plural rules match the template.
• Add the locale to supportedLocales in MaterialApp (see lib/main.dart).
• Regenerate: flutter gen-l10n.

Best Practices

• Key naming: use lowerCamelCase (e.g., loginButton, errorMessage).
• Include @ metadata with description for context and placeholders with examples.
• Prefer ICU plural/select syntax for quantities and genders.
• Avoid concatenating strings at runtime; use placeholders in ARB.

In‑App Locale Switching

• Open the Profile page → Settings tile → choose System, English, Deutsch, Français, or Italiano.
• Selection persists across app launches.

Troubleshooting

• Build fails with ARB placeholder errors:
  • Ensure every placeholder has an example string and correct type.
• Missing translation at runtime:
  • Flutter falls back to English; search for hard‑coded strings and replace with AppLocalizations.
• iOS strings not changing:
  • Restart the app after changing system language or use the in‑app language selector.

References

• Flutter localization: https://docs.flutter.dev/ui/accessibility-and-localization/internationalization
• Intl package: https://pub.dev/packages/intl