React Native Localization

26 February 2024

Localization in React Native

Ed Robinson, Lead Software Engineer

Introduction to React Native Localization

In this section, we are going to delve into the world of React Native Localization. We'll begin by understanding what React Native Localization means, the importance of localization in apps, and the differences between Internationalization and Localization.

Understanding React Native Localization

Localization is the process of adapting an application's interface and functionality to suit a specific culture or locality. For developers harnessing the power of React Native, localization is a must. React Native is a popular framework for cross-platform mobile application development. Leveraging the JavaScript library i18n-js, react-native-localization, and the expo-localization package, React Native provides practical and efficient solutions to implement localization in the apps.

For example, we can use the expo-localization library to fetch the user's language and locale; the i18n-js package helps us return and manage localized strings. Dynamic values can be inserted into localized string through Interpolation. Number and currency localization can be effectively handled using the Intl.NumberFormat object. For handling complex plural rules, make-plural can be an efficient tool.

The Importance of Localization in Apps

Localization plays a key role in crafting a user-friendly and inclusive application. It ensures that your application appeals to a wider audience, as it accommodates for different languages, locale-specific data formats (like dates and currency), as well as different cultural contexts. By implementing localization in your React Native app, your app will be more accessible and engaging to the global userbase.

This is where choosing a headless Content Management System (CMS) such as caisy plays a pivotal role. Caisy allows you to manage and deliver localized content in a more efficient and streamlined way. Leveraging headless CMS, you can separate the content layer from the presentation layer of your application, making the content more flexible to be displayed across multiple channels in different languages. For developers dealing with React Native localization, a headless CMS like caisy can drastically simplify the process of managing and implementing localized content.

Differences between Internationalization and Localization

Internationalization and localization are related but distinct concepts. While they often occur concurrently, their goals and processes are different.

Internationalization is the design and development of an application that makes it easy to adapt for different languages, regional differences, and technical requirements of a region or country. It is a broader, preparatory process, ensuring the application can be adapted to various locales without architectural changes.

Localization, on the other hand, is the actual adaptation of the application to a specific locale. It involves translating the user interface, resizing dialog boxes, customizing features, and more.

React Native offers support for both Internationalization and Localization. As we delve deeper into this guide, we'll familiarize ourselves with effective strategies, libraries, benefits, troubleshooting, and real-world implementations of React Native localization.

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Getting Started with Localization in React Native

React Native localization requires an understanding of some specific libraries and concepts. In this section, we will dive deep into them.

Initial Setup and Required Libraries

We start by setting up our React Native project with the necessary packages. Some of these packages include expo, expo-localization, i18n-js, make-plural, react-native, and react. The Expo framework offers significant advantages for react native localization.

Fetching User's Language and Locale

With expo-localization, we can fetch user's locale and use it in our application. The package gives us information about the user's locale and language settings.

Returning Localized Strings with 'i18n-js'

Next, we integrate the i18n-js package. It helps us to create and manage localization files with translations for different languages. Using the I18n object, we translate strings in the app, thus ensuring the app can cater to a wider audience.

Understanding and Implementing Interpolation

Interpolation is a technique used to dynamically insert values into localized strings. It plays a vital role in apps that require real-time data display, say, a weather app.

Localizing Currency and Numbers

We use the Intl.NumberFormat object for localizing currency and numbers. It assists in formatting the price with the user's country's currency symbol and handling number formatting.

Localizing Dates

Dates, just like languages, are presented differently across various locales. Using Intl.DateTimeFormat, we format the current date based on user's locale.

Handling Plurals and Complex Plurals with 'make-plural' and 'i18n-js'

Dealing with plurals and complex plurals rules is an area where i18n-js and make-plural come in handy. We define different plural categories in the localization file and use these packages to handle correct pluralization.

Localizing Measurement

We use user's preferred measurement system (metric or imperial) in our app for localizing measurements.

Adding Language Toggle Buttons

To enhance user experience, we can add language toggle buttons. These buttons allow users to change the app language from within the app itself.

Right-to-Left (RTL) Support

Lastly, we set the "supportsRTL": true flag in app.json to enable support for languages that are written from right to left. We can use React Native's style properties to auto-adjust the layout based on the app's language direction.

That sums up our process to set up a localization project in React Native. These steps ensure that our React Native app can be used by a diverse range of users across different locales. Getting localization right is a crucial part of delivering an inclusive and user-friendly app.

Effective Strategies and Libraries for React Native Localization

Device Locale Strategy

The device locale strategy is one way to perform localization in a React Native app. This involves determining the user's preferred language and applying it throughout the app. This strategy uses the expo-localization library which fetches the user's locale. Here is how you can get the user's language and locale:

import * as Localization from 'expo-localization';


The locale can include both the language and region (e.g., en-US or ja-JP).

Custom Localization Strategy

In the custom localization strategy, the user is given the ability to change the application language from within the app itself. For the custom localization strategy, it is necessary to implement UI elements that enable the user to choose a language preference out of the ones supported by the app. Once the user selects a language, it is important to prompt re-rendering to reflect the new language settings.

Overview of 'i18n-js', 'make-plural', 'expo-localization', and 'react-native-localization' Libraries

The libraries i18n-js, make-plural, expo-localization, and react-native-localization greatly simplify the localization process. The i18n-js package serves to return localized strings and handle complex plurals. Here is a small example of how it is used:

import I18n from 'i18n-js';

//configuring the I18n object
I18n.translations = {
  en: {
    greeting: 'Hello'
  ja: {
    greeting: 'こんにちは'

console.log(I18n.t('greeting')); // prints 'Hello' or 'こんにちは' based on I18n.locale

make-plural is used for dealing with complex pluralization rules for languages. The expo-localization package enables fetching user's locale, localizing dates, currency and units. The react-native-localization library can be used for localizing strings, plurals and loading images based on the device language or region.

Considerations for Efficient Localization

For efficient localization, it is recommended to organize translations in separate files on a per-language basis. This makes maintaining and managing translations easier. Internationalizing numbers, currencies, dates, and measurements is also important. JavaScript has built-in methods for these, like using Intl.NumberFormat or Intl.DateTimeFormat.

Also consider right-to-left language support. RTL rendering can be enabled by setting the "supportsRTL": true flag in app.json, and you can manage the layout direction based on language using React Native's styles.

Remember, establishing a solid localization setup from the start simplifies work when adding new languages or interfaces in the future. Therefore, investing time in the localization process is crucial for making your app as user-friendly and versatile as possible.

Benefits of Localization in React Native

Localization in React Native is a key factor for successful global expansion of your application. It not only facilitates reaching wider audiences but also provides several other vital advantages for your app.

Here's an overview of the general benefits of localization.

Increasing Accessibility and User Engagement

React Native localization ensures that your app is accessible to a broad base of users. It makes the app user-friendly by adapting to regional preferences and cultural norms, creating an environment that feels native to the user. More so, a localized app is known to improve user engagement significantly, as users are likely to interact more with an application that respects and reflects their language and culture.

Attaining Competitive Advantage

On the global platform, React Native localization gives your app a competitive advantage. With a large number of mobile applications vying for user attention, a localized app stands out, as it caters to a larger user base addressing their language and cultural nuances. Furthermore, by leveraging libraries such as i18n-js and react-intl, localization can be implemented quickly thus giving you an edge over competitors.

Ensuring Legal Compliance

Localization also helps in adhering to legal requirements of the region your app operates in. Certain regions have specific laws concerning language usage in mobile applications and failure to comply with these can lead to legal issues. Hence, React Native Localization is vital for your app to remain compliant with such laws.

Implementing Language Switching

Implementing language switching in your app can enhance the user experience as it allows users to switch to their preferred language dynamically. This can be achieved by updating the selected language in the localization library, for instance i18n.locale. For handling Right to Left (RTL) languages, React Native has a built-in I18nManager module which can be utilized.

i18n.locale = 'fr';

Role of Localization in Successful Internationalization

Localization plays an important role in the success of internationalization of a React Native application. By organizing translation files, initializing the localization library and implementing language switching, your app is prepared for a global audience. Remember, best practices like using tokens instead of hardcoding values, avoiding string concatenation and supporting plurals and gender neutrality will make your localized app more efficient.

Troubleshooting Common Issues in React Native Localization

As developers, we inevitably encounter challenges during localization in our React Native application. This section aims to highlight some common issues and guide you through resolving them.

Issue with 'react-native-localize' and 'i18n-js'

A known issue in the world of React Native localization concerns an authentication error that occurs due to a version upgrade to react-native-localize 1.0.1. This version shows compatibility issues on both Android and iOS platforms alike.

  Error: react-native-localize: NativeModule.RNLocalize is null

To resolve this issue, you may consider downgrading to react-native-localize version 1.0.0 or resorting to manual linking. Other solutions include clearing the Metro bundler cache or upgrading your React Native version.

FolderPath and UI Rerendering Issues

When applying localization using libraries such as i18n-js,moment, and lodash.memoize, you must understand the intricacies of folder structure and UI rerendering tactics. The recommended simple approach is to translate JSON locale strings using the Google Cloud Translate API. You might also leverage React Context to monitor language changes in your application and render the UI as needed.

Retrieving Data from AsyncStorage

A common dilemma developers encounter when localizing React Native apps, revolves around retrieving data from AsyncStorage. In one scenario, the locale is always set to "en" regardless of varying values.

  if (value !== null) {
    this.setState({locale: value});
  } else {
    this.setState({locale: "en"});

This particular snippet checks for a value in AsyncStorage and assigns a locale accordingly. However, the issue remains that even if the value is "ar", the app sees it as null and assigns "en", defaulting to English. This issue, while common, requires additional investigation on a case by case basis.

Common Solution Strategies

When faced with React Native localization issues, there are a few go-to strategies that can assist in resolving them. Checking the versions of your libraries and React Native itself can help, as can clearing your Metro bundler cache. Leveraging well-documented and robust libraries for tasks such as handling translations and data storage increases consistency and reduces errors in your app. However, every issue is unique, and sometimes a deep dive into the root source of the error is the only way to grasp a thorough understanding of the issue and devise an appropriate solution.

Case Studies and Real-world Implementations of React Native Localization

Using React-i18next and Lokalise for Effective Localization

React Native localization is an integral part of app development that goes beyond simple translation. It entails cultural semantics, the complexities of interpolation, and pluralization. Many developers opt for frameworks like react-i18next that simplify the internationalization of React or React Native projects.

react-i18next requires the installation of necessary packages like Expo and navigation. The implementation process is fairly straightforward, with steps covering project structure creation, settings configuration, navigation setup, and the handling of more advanced features like interpolation and pluralization.

Translation files, often stored in the JSON format, can be efficiently loaded using libraries like react-native-localization or i18next-js.

For a more streamlined localization process, tools and services like Lokalise offer several beneficial features, such as API, CLI integrations, code repository synchronization, over-the-air SDKs for translation delivery, duplicate key detection, context sharing, cross-platform capabilities, and translation services.

How to Generate Higher ROI and User Satisfaction with Localization

Localization in React Native serves more than just cultural adaptation. It is an essential feature that helps applications reach a broader audience and deliver an enhanced user experience, leading to higher ROI and user satisfaction.

While React Native localization may initially seem challenging, the use of effective frameworks and tools simplifies the process. Moreover, strategies that are meticulously planned and implemented can generate substantial returns, paving the way towards achieving a competitive edge in the digital marketplace.

This concludes our exploration of mastering React Native localization. We delved into its significance, strategies, common pitfalls, and real-world implementations. But remember, efficiency in your workflow is just as critical as the technologies you use.

This is where a tool like caisy comes into play. Caisy is a high-performing unique headless CMS, perfectly tailored for developers and agency workflows, that offers a built-in localization feature. With impressive speed and a user-friendly interface, it promotes smooth content creation and management.

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With its scalability and multi-tenancy system, caisy caters directly to the needs of developers. This makes it an optimal choice for those seeking flexibility and efficiency in their tools. In line with this, the concluding thoughts of our discussion on React Native localization reiterate the importance of versatile tools like caisy in a developer's toolbox. So, why not give caisy a try and explore its wide array of features that make it a significant addition to your technology stack?

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