Localization
Modern iOS localization using String Catalogs (.xcstrings) for managing translations, plural forms, and locale-aware content. Supports SwiftUI's LocalizedStringKey and String(localized:) APIs.
Reference Loading Guide
ALWAYS load reference files if there is even a small chance the content may be required. It's better to have the context than to miss a pattern or make a mistake.
| Reference | Load When | |-----------|-----------| | String Catalogs | Setting up or using Xcode 15+ String Catalogs | | Pluralization | Handling plural forms, stringsdict migration | | Formatting | Date, number, currency locale-aware formatting | | RTL Support | Right-to-left layouts, semantic directions |
Core Workflow
- Create String Catalog in Xcode (File > New > String Catalog)
- Mark strings with
String(localized:comment:)or use SwiftUI's automatic extraction - Add plural variants in String Catalog editor where needed
- Test with pseudo-localization (Scheme > Run > Options > App Language)
- Export for translation (File > Export Localizations)
Key Patterns
// SwiftUI - automatic localization
Text("Welcome")
Button("Continue") { }
// Explicit localization with context
let title = String(localized: "Settings", comment: "Navigation title")
// Deferred localization for custom views
struct CardView: View {
let title: LocalizedStringResource
var body: some View { Text(title) }
}
Build Settings
- Use Compiler to Extract Swift Strings: Yes
- Localization Prefers String Catalogs: Yes
Common Mistakes
-
Forgetting String Catalog in Build Phases — Adding String Catalog but forgetting to check "Localize" in File Inspector means it's not embedded. Always verify in Build Phases > Copy Bundle Resources.
-
Pseudo-localization not tested — Not running your app with pseudo-localization (German/Chinese pseudo-locale) means you miss text overflow and RTL issues. Always test with pseudo-localization before translation.
-
Hardcoded strings anywhere — Even one hardcoded string outside the String Catalog breaks extraction and automation. Use
String(localized:)everywhere or useLocalizedStringResourcefor deferred localization. -
Context loss in translations — Providing no comment for translators means they guess context and get it wrong. Add comments explaining where the string appears and what it means.
-
RTL layouts not tested — Assuming LTR layout works for RTL languages (Arabic, Hebrew) fails miserably. Test with system language set to Arabic and verify semantic directions are used.