iOS app localization: A complete guide

Master iOS app localization to connect globally, boost downloads, and improve user experience. Learn key strategies and best practices here.

iOS app localization is the key to getting diverse audiences around the world to engage with your app. Localization is much more than a simple translation of your iOS app language. Proper localization allows you to adapt your app’s content to match users’ languages, cultures, and expectations. This creates a seamless experience for your audience and maximizes your chances of success.

At Smartcat, we offer an easy-to-use software localization tool that combines AI and human workflows. Trusted by 25% of Fortune 500 companies, we’ve helped industry leaders achieve international success. Read on to discover the advantages of localization as well as the localization best practices for iOS.

iOS refers to the operating system (OS) that runs on Apple’s mobile devices, such as iPhones. Previously, iPads also ran iOS. However, in 2019, Apple introduced iPadOS to support the unique features of the tablet range.

However, it would be a mistake for developers to focus exclusively on the US market.

According to data from Statcounter :

• There are over 1.46 billion active iPhone users in the world.

• As of 2024, the iPhone had a 28.46% market share in the global smartphone industry.

• This includes a 20.78% share in Asia and 32.08% in Europe, both regions with high linguistic diversity.

Localization means preparing your app to operate in different languages and cultural contexts. This includes translating content and adapting formats like dates, times, and currencies. It also involves adjusting design elements and user interface (UI) components.

When developing your app, it’s crucial to think beyond the original language. This is true whether you’re developing for iOS, Android, or desktop platforms like Windows or Linux.

Localization ensures that users can interact with your app naturally in their native language. It’s about more than just translation—it’s about delivering a user experience that feels local and familiar. Neglecting localization means missing out on millions of potential users. With millions of apps on the App Store, standing out with a well-localized experience is essential.

Localization allows you to speak directly to users in their own language. This builds trust and improves the user experience. When users feel comfortable with your app, they’re more likely to engage and recommend it to others.

Operating an app in a different language or working with a poor translation are frustrating experiences! A user will always prefer an app that’s easy to understand and operate—and that starts with language.

Localizing your app allows you to tap into emerging markets and underserved regions. Offering your app in local languages gives you an edge over competitors who haven’t localized.

Localizing increases your app’s chances of being downloaded and used by a wider audience. This includes those valuable new users in emerging markets who might be starting up their first iPhone—and falling in love with your app. To capture this audience before your competition does, plan your localization from day one.

Localized apps tend to get more downloads.

Some of the most widely used apps in the world, such as TikTok, owe their success to effective localization strategies.

When creating an app for iOS, Apple suggests utilizing its integrated development environment (IDE), called Xcode.

This platform allows you to handle every stage of the development process, including:

1. Writing the code

2. Setting up the app’s structure

3. Designing the user interface

4. Testing and troubleshooting

5. Enhancing app performance

6. Choosing a business model

Xcode primarily supports iOS development using Swift and Objective-C as your programming framework. Other languages that can be used to develop iOS apps include:

• JavaScript (with React Native)

• Dart (with Flutter)

• C# (+ MAUI).

Xcode is exclusive to Mac computers, though you can access it from other operating systems through virtualization tools. You can also use a cloud-based service like MacStadium that offers remote access to Xcode.

While developing iOS apps without Xcode is possible, it’s much more complex. Our localization guide for iOS apps assumes that you will be using Xcode as a development environment.

Start by planning your localization strategy during development. This can include:

• Structuring your code and resources to support multiple languages and regions.

• Considering cultural differences and how they affect content display. Some cultures may prefer more conservative fashion or more polite language than others. A funny joke in one country could be deemed offensive somewhere else.

• Check your graphic design for similar issues. For example, in China, red is considered a ‘lucky’ color, but white is associated with death.

• Getting input from your marketing, design, and development teams to ensure a smooth localization.

• Consulting native speakers of your target audience’s language.

Xcode is your primary tool for iOS localization. Get started with iOS language controls by enabling localization in your Xcode project settings.

Use localizable.strings files to manage your app’s text resources. Each language will have its own.strings file for easy translation.

1. Open Xcode and go to your project settings.

2. In the Info tab, under Localization, click the "+" button and select the languages you want to support.

3. Xcode will automatically create the appropriate files for each locale.

Focus on languages spoken by your app’s target audience. Use data from existing user analytics or market research to choose the best languages. For example, if your app is gaining traction in Latin America, Spanish and Portuguese should be your top priorities.

It’s important to note that there can be significant differences between variants of the same language in different countries.

For example, versions of Spanish spoken in the various Latin American countries differ from each other and are different again to European Spanish. German and Swiss German also have alternative ways of expressing certain concepts. A word like “football” refers to different sports when understood by a British or American user. Remember these regional and international differences when sourcing reviewers for your app project!

Prioritize markets with high growth potential or strong existing demand. Consider countries where your competitors have not yet localized, as this could be your opportunity to capture new users.

iOS apps often rely on the device’s system settings to automatically choose the application locale. However, developers can also manually set or override it as needed.

Different languages vary in text length and layout. For example, German text often runs longer, while Chinese uses fewer characters. Make sure to:

• Design flexible layouts to accommodate variations.

• Test your app for both right-to-left (RTL) and left-to-right (LTR) languages.

• Ensure that your UI can handle changes in text direction, length, and word order. This includes expanding text boxes, ensuring icons and images are correct, and adjusting for varying character sizes.

In iOS development, the Locale class and NSLocale object are used to configure and retrieve locale information. iOS apps often rely on the device's system settings to automatically choose the application locale, but developers can also manually set or override it as needed.

All translatable text in iOS apps is stored in localizable strings files. These are key-value pairs used to manage language-specific content. Each text element is assigned a unique key, making it easy to translate and update.

1. In Xcode, select your.strings file and add the corresponding translations for each locale.

2. Each text element will look something like: "HelloWorld" = "Bonjour le monde";

3. Save these changes and recompile your app to see the updated content.

Xcode has limited built-in localization tools. However, you can also use a specialized translation management system (TMS) to streamline the localization process.

Smartcat is a TMS platform used by industry-leading companies to achieve efficient, professional localization. Its software integrates directly with your localization files and manages translations for 280+ languages. Using a TMS ensures consistency and quality by providing automated translations and enabling human translators to review content.

Smartcat allows you to:

1. Import your . strings files directly from your Git repository with a built-in iOS translation plugin .

2. Use AI-based translation suggestions for speed and cost efficiency. Smartcat’s AI translator learns your preferences and becomes even faster the more you use it.

3. Manage translation memories and glossaries to maintain consistency across all your projects and languages.

4. Easily add language experts and reviewers to your team via the Smartcat Marketplace. The Smartcat platform handles sourcing, contracting, and procurement, saving you time.

5. Easily collaborate on a single platform with an unlimited number of seats for in-house and external team members.

6. Streamline your workflows by automatically pushing translated content back to Git.

Although various app localization services vendors are on the market, a platform like Smartcat allows you to stay in control of the entire process, end-to-end. Book a free demo to find out why top tech companies use Smartcat for localization.

Implementing localization in your iOS app

UI elements in storyboards and XIB files need to be localized separately. Use Xcode’s Interface Builder to add localization support. Create separate.strings files for each UI component and ensure every element is correctly linked.

1. Select the storyboard file in Xcode.

2. Open the File Inspector and enable localization for the storyboard.

3. Xcode will create a.strings file for each supported language.

Avoid hardcoding strings in your code. Use NSLocalizedString to dynamically load text from the relevant.strings file. This function allows your app to automatically switch languages based on the user’s settings.

In Swift, this could look like :

let greeting = NSLocalizedString("HelloWorld", comment: "Greeting shown to the user")

This line pulls the translated value of HelloWorld from the.strings file.

Languages often use different sentence structures. Use string formatting to insert dynamic content, such as usernames or dates, without disrupting grammar or flow.

In Swift, instead of "Hello, %@!", you can use:

let welcomeMessage = String(format: NSLocalizedString("Hello, %@!", comment: ""), userName)

This approach adapts easily to varying grammatical rules, giving you more options when it comes to localization.

Beyond simple language differences, it’s crucial to keep in mind how different countries present information. This includes things like dates, times, and measurements.

Use the following formatters to ensure content displays correctly across different languages and regions:

1. NumberFormatter

Format numbers, currencies, and percentages according to the user’s locale. For example, £5.50 (UK), vs. 5,30€ (Spain)

2. DateFormatter

Format dates and times based on the locale, including variations in calendar formats, e.g., dd/mm/yyyy vs. mm/dd/yyyyy.

3. RelativeDateTimeFormatter

Display relative dates (e.g., “Yesterday,” “Tomorrow”) that adjust according to the user’s locale.

4. ISO8601DateFormatter

Format dates in the ISO 8601 standard (e.g., YYYY-MM-DDTHH:MM:SSZ). This is particularly useful for exchanging date-time data between different locales or systems.

5. MeasurementFormatter

Localize units of measurement like distance, speed, or weight. You can set your app to automatically adjust for different unit systems (e.g., metric vs. imperial) based on the locale.

6. ListFormatter

Display lists (e.g., ["Apples", "Bananas", "Oranges"]) in a natural format for the locale.

7. DateComponentsFormatter

Format duration strings (e.g., “2 hours, 15 minutes”) based on the locale.

8. TextFormatters for Plurals and Genders

Use String.localizedStringWithFormat to handle pluralization and gender rules in strings.

Using these formatters ensures that text, numbers, dates, and other units are displayed correctly, enhancing the user experience across different locales and languages.

Testing is crucial to ensure everything works as expected. In iOS development, you can use Xcode’s built-in Simulator tool to test multiple locales.

Here’s some tips on testing in Xcode Simulator:

Use real devices

Outside of the development environment is the real world of user experience. It’s crucial to test on real devices to check for layout issues and ensure all text is translated correctly. You’ll want to have several iPhones on hand for this, including older models that might be running previous iOS versions.

Test with pseudo-localization

Use p seudo-localization to simulate different languages without needing full translations. Pseudo-localization is a software testing technique that replaces the original text with a different phrase in the original language.

For example, a pseudo-localized version of the phrase “manage user preferences” might look like:

"[!!! 𝓂åñåɡê üśëŕ ƥŕéƒéŕéñçëś !!!]"

Pseudo-localization adds extra characters, special symbols, and accents to simulate the look and feel of translated text. It helps developers identify layout issues or hardcoded strings that might not be obvious during standard localization testing.

In your testing phase, l ook out for:

• Missing translations (the original text is left in place)

• Text overflow (text spills out of its intended space)

• Layout misalignment (UI elements out of place)

Use automated tools and manual testing to catch and fix these issues early. For example, use Apple’s genstrings to automatically find and manage localized text.

The best way to test the accuracy of your localization is to consult a native speaker. Ideally, your language expert will also be living in or is intimately familiar with your target country. That way, they will be up to date on the nuances of both cultural traditions and current events.

Smartcat is an end-to-end translation management platform that makes mobile app localization efficient and scalable. It streamlines the localization process to just a few simple steps.

Here’s how to localize an iOS on the Smartcat platform:

1. Create a software localization project Log in to Smartcat and create a new localization project. Choose “iOS app” as the project type and upload your.strings files.

2. Set up translation workflows You can set up AI-only translations, human-only translations, or AI translation followed by human review (recommended). Smartcat’s translation memory and glossaries ensure consistent terminology.

3. Select professional translators Smartcat makes it easy to find and onboard external language experts to help your team. Choose from Smartcat’s marketplace of 500,000 professional translators. Select experts with experience in your app’s niche or software localization for the most optimal localization results.

4. Translate and review Use Smartcat’s real-time collaboration features to manage translation and review. Track progress using the project dashboard.

5. Export the localized files Once translations are complete, export the.strings files back into your Xcode project. You can also automate this process using Smartcat’s iOS integration.

6. Test and iterate Smartcat’s automated quality assurance features help identify translation errors. Before launching, run tests in your app’s staging environment.

Read more: Localization testing – your ultimate step-by-step guide

Launching and monitoring your localized app

When submitting to The App Store, update your app metadata for each language. This includes localized app names, descriptions, and keywords. Use culturally relevant images and videos to appeal to each market.

Track metrics like downloads, user retention, and engagement in each localized market. Gather insights using in-app surveys, reviews, and analytics. Refine your content and adjust translations based on feedback.

Take a look at these best practices to ensure a smooth iOS localization process.

1. Plan localization from the start

Structure your app to support multiple languages from day one. Retroactive localization is more complex and costly.

2. Use localized resources for each language

Create separate.strings files for each language. This keeps your translations organized and easy to update.

3. Keep UI elements flexible

Design your UI to adapt to different text lengths and layouts. This ensures a smooth experience in all languages.

4. Avoid hardcoding text in your code

All text should be stored in.strings files. This makes it easy to update translations without touching the core code.

5. Regularly update translations

As you add new features, make sure to update your translations. Consistent updates help maintain a high-quality user experience.

6. Use Auto Layout in Xcode

Auto Layout allows your app’s UI to adjust dynamically based on the content size and direction.

7. Support right-to-left languages

Use UIView’s semantic properties to support RTL languages, ensuring text and UI elements align correctly.

8. Leverage translation management systems

Utilize dedicated AI-powered translation platforms like Smartcat to automate repetitive tasks.

9. Test regularly in different locales

Use Xcode’s simulator and real devices to catch potential issues early on.

Take inspiration from these frontrunners in iOS app localization.

Spotify is the largest and most popular audio streaming subscription service in the world, with an estimated 286 million users. This large user base reflects the platform's global reach and popularity. Spotify is available in 79 languages. It goes beyond simple translation by adapting its app for cultural preferences. For instance, Spotify curates its playlists and recommendations based on regional music trends.

Airbnb localized its app into 62 languages and adapted its content to reflect local cultural expectations. This included modifying icons, images, and descriptions to resonate with users in different regions.

Netflix offers its platform in over 20 languages. Its localization strategy includes translating subtitles, adapting genre names, and creating culturally relevant promotional content for each market.

By localizing your app, you connect with users worldwide, increase downloads, and stand out in a crowded app store.

Ready to take localization to the next level?

Sign up for a free trial with Smartcat and

• Smartcat’s guide to software localization

• Smartcat’s iOS integration

• Localization case studies and success stories

• Localization trends for 2024

• Apple’s localization guide for iOS