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 use LocalizedStringResource for 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.