What file formats does i18n Agent support?

i18n Agent supports 9+ file formats including JSON, YAML, CSV, XML, Markdown, Properties, and more. The service preserves structure and formatting automatically.

How much does i18n Agent cost?

i18n Agent costs €0.01 per word, which is significantly more affordable than traditional translation services that typically charge €0.15-0.25 per word.

What is MCP integration?

MCP (Model Context Protocol) integration allows i18n Agent to work directly with AI development tools like Claude Code, Cursor, and other AI-powered development environments for seamless translation workflows.

What is iOS localization and how does it work?

iOS localization is the process of adapting your app for different languages and regions. Xcode uses .strings or .xcstrings files to map string keys to translations. At runtime, iOS automatically loads the correct translation based on the user's device language.

Should I use Localizable.strings or String Catalogs?

For new projects targeting iOS 16+, use String Catalogs (.xcstrings). They offer a visual editor in Xcode, automatic string extraction, and built-in plural support. For existing projects or those needing backward compatibility, Localizable.strings still works perfectly and is supported by all localization tools.

How do I handle pluralization in iOS apps?

Use .stringsdict files for traditional .strings setups or the built-in plural editor in String Catalogs. Both support all CLDR plural categories (zero, one, two, few, many, other), which is essential for languages like Arabic, Russian, and Polish that have complex plural rules.

Why use Fastlane for App Store metadata?

Fastlane's deliver tool stores your App Store metadata (name, description, keywords, release notes) as plain text files in your repository. This makes metadata version-controlled, reviewable in pull requests, and translatable with the same tools you use for app strings.

Can I automate iOS app translations?

Yes. Once your .strings, .xcstrings, or Fastlane metadata files are set up, i18n Agent can translate them all from your IDE. It understands iOS string formats, preserves placeholders like %@ and %d, and handles plural rules correctly for each target language.

The Complete Guide to iOS App Localization

Name: i18n Agent
Price: 0.01 EUR
Rating: 4.8 (127 reviews)
Author: i18n Agent

From Localizable.strings to App Store metadata: localize your iOS app with Xcode, SwiftUI, Fastlane, and automated AI translation.

Set Up Localizable.strings

Start with the standard iOS localization file. Create Localizable.strings in your Base.lproj folder and add your app's user-facing strings as key-value pairs.

Base.lproj/Localizable.strings

// Base.lproj/Localizable.strings

"welcome_title" = "Welcome to MyApp";
"login_button" = "Sign In";
"settings_label" = "Settings";
"greeting" = "Hello, %@!";

Configure String Catalogs (Xcode 15+)

Xcode 15 introduced String Catalogs (.xcstrings) — a modern replacement for .strings files. Xcode automatically extracts localizable strings from your SwiftUI views and manages translations in a visual editor.

Localizable.xcstrings

// Xcode 15+ String Catalog (Localizable.xcstrings)
// Xcode automatically extracts strings from your code
// and manages translations in a visual editor.

// In SwiftUI, strings are automatically localizable:
Text("Welcome to MyApp")
Text("Hello, \(userName)!")

// Mark strings explicitly:
let title = String(localized: "welcome_title")

Use NSLocalizedString in Code

Access localized strings in SwiftUI with automatic string literal localization, or use NSLocalizedString for UIKit. SwiftUI's Text view localizes strings by default — no extra wrapper needed.

ContentView.swift

import SwiftUI

struct ContentView: View {
    var body: some View {
        VStack {
            // SwiftUI auto-localizes string literals
            Text("welcome_title")

            // With variables
            Text("Hello, \(userName)!")

            // UIKit style
            let title = NSLocalizedString(
                "settings_label",
                comment: "Settings screen title"
            )
        }
    }
}

Handle Plurals and Variables

iOS uses .stringsdict files for plural rules, supporting all CLDR plural categories (zero, one, two, few, many, other). String Catalogs handle plurals visually in Xcode's editor.

Localizable.stringsdict

<!-- Localizable.stringsdict -->
<?xml version="1.0" encoding="UTF-8"?>
<plist version="1.0">
<dict>
    <key>items_count</key>
    <dict>
        <key>NSStringLocalizedFormatKey</key>
        <string>%#@count@</string>
        <key>count</key>
        <dict>
            <key>NSStringFormatSpecTypeKey</key>
            <string>NSStringPluralRuleType</string>
            <key>one</key>
            <string>%d item</string>
            <key>other</key>
            <string>%d items</string>
        </dict>
    </dict>
</dict>
</plist>

Manage App Store Metadata with Fastlane

Use Fastlane's deliver tool to keep App Store metadata — app name, description, keywords, release notes — version-controlled in your repo. Translate metadata files alongside your app strings for a fully localized App Store presence.

Gemfile + Terminal

# Gemfile
source "https://rubygems.org"
gem "fastlane"

# Terminal
$ bundle install
$ bundle exec fastlane deliver init

# Directory structure created:
# fastlane/metadata/en-US/
#   ├── name.txt
#   ├── subtitle.txt
#   ├── description.txt
#   ├── keywords.txt
#   ├── release_notes.txt
#   └── promotional_text.txt
# fastlane/metadata/de-DE/
#   ├── ...
# fastlane/metadata/ja/
#   ├── ...

# Push metadata to App Store Connect:
$ bundle exec fastlane deliver

Automate with i18n Agent

With your localization files and App Store metadata in place, automate translation of both .strings files and Fastlane metadata directories directly from your IDE.

Terminal

# Translate your .strings files to multiple languages
> Translate Base.lproj/Localizable.strings
  to Japanese, German, and Spanish

# Translate App Store metadata too
> Translate fastlane/metadata/en-US/
  to de-DE, ja, es-MX

✓ 6 files translated in 3.2s

Optional: Smart Locale Fallback with LocaleChain

By default, iOS falls back to your development language when a user's exact locale isn't available. A pt-BR user with only pt-PT translations sees English instead of Portuguese. LocaleChain is an open-source Swift package that fixes this by walking a configurable fallback chain — so regional variants always find the closest available translation.

Works with NSLocalizedString, SwiftUI Text(), Storyboard/XIB, and .stringsdict plurals. Includes pre-configured chains for 8+ language families. View on GitHub →

Package Dependencies

// Swift Package Manager
// File > Add Package Dependencies >
// https://github.com/i18n-agent/ios-localechain.git

MyApp.swift

import LocaleChain

// In your App init or AppDelegate:
LocaleChain.configure()  // Activates all default chains

// pt-BR user with only pt-PT translations?
// → Shows Portuguese instead of falling back to English

// Custom overrides for your specific locales:
LocaleChain.configure(
    overrides: ["es-MX": ["es-419", "es"]]
)