Class to localize the ReactNative interface.

Use react-localization if you want to share code with a React project.

I just needed a dead simple way to internationalize my first React Native app.

At the beginning I thought I'd expose the native iOS internationalization API (NSLocalizedString macro) to React Native, but then I've opted for a solution that seems, at least to me, more in the spirit of React (and I hope better performance wise).

In this implementation we can keep the localized strings in the same file of the React View in a similar way of how Styles are implemented (I don't deny that this approach could lead to some duplications in the translated strings, but it could be feasible to create a CommonJS module to use as common source of the strings, requiring it in the different views).

The Javascript library uses a native library (ReactLocalization) to get the current interface language, then it loads and displays the strings matching the current interface locale or the default language (the first one if a match is not found) if a specific localization can't be found.

It's possible to force a language different from the interface one.

The easiest way to install is to type just 2 commands inside your react-native project folder and you are ready to go:

npm install react-native-localization --save
react-native link

Don´t forget to restart the app / node server or you will see an error.

If you're installing for Android and still experiencing problems check if step 4 of "Manual installation Android" has been automatically executed by the linker.

1. npm install --save react-native-localization
2. In the XCode's "Project navigator", right click on Libraries folder under your project ➜ Add Files to <...>
3. Go to node_modules ➜ react-native-localization and add the ReactNativeLocalization.xcodeproj file
4. Add libReactNativeLocalization.a to Build Phases -> Link Binary With Libraries
5. Build and run

1. npm install --save react-native-localization

2. In android/setting.gradle

   ...
   include ':react-native-localization', ':app'
   project(':react-native-localization').projectDir = new File(rootProject.projectDir, '../node_modules/react-native-localization/android')

3. In android/app/build.gradle

   ...
   dependencies {
       ...
       compile project(':react-native-localization')
   }

4. register module (in MainApplication.java)

   import com.babisoft.ReactNativeLocalization.ReactNativeLocalizationPackage; // <--- import
   
   public class MainApplication extends Application implements ReactApplication {
     ......
       @Override
       protected List<ReactPackage> getPackages() {
         return Arrays.<ReactPackage>asList(
             new MainReactPackage(),
             new ReactNativeLocalizationPackage()
         );
       }
     ......
   }

(Thanks to @rebeccahughes for showing by example how to create an android module for React Native)

In the React class that you want to localize require the library and define the strings object passing to the constructor a simple object containing a language key (i.e. en, it, fr..) and then a list of key-value pairs with the needed localized strings.

// ES6 module syntax
import LocalizedStrings from 'react-native-localization';

// CommonJS syntax
// let LocalizedStrings  = require ('react-native-localization');

let strings = new LocalizedStrings({
 "en-US":{
   how:"How do you want your egg today?",
   boiledEgg:"Boiled egg",
   softBoiledEgg:"Soft-boiled egg",
   choice:"How to choose the egg"
 },
 en:{
   how:"How do you want your egg today?",
   boiledEgg:"Boiled egg",
   softBoiledEgg:"Soft-boiled egg",
   choice:"How to choose the egg"
 },
 it: {
   how:"Come vuoi il tuo uovo oggi?",
   boiledEgg:"Uovo sodo",
   softBoiledEgg:"Uovo alla coque",
   choice:"Come scegliere l'uovo"
 }
});

Then use the strings object literal directly in the render method accessing the key of the localized string.

<Text style={styles.title}>
  {strings.how}
</Text>

The first language is considered the default one, so if a translation is missing for the selected language, the default one is shown and a line is written to the log as a reminder.

• setLanguage(languageCode) - to force manually a particular language
• getLanguage() - to get the current displayed language
• getInterfaceLanguage() - to get the current device interface language
• formatString() - to format the passed string replacing its placeholders with the other arguments strings

  en:{
    bread:"bread",
    butter:"butter",
    question:"I'd like {0} and {1}, or just {0}"
  }
  ...
  strings.formatString(strings.question, strings.bread, strings.butter)

Beware: do not define a string key as formatString or language!

• getAvailableLanguages() - to get an array of the languages passed in the constructor

To force a particular language use something like this:

_onSetLanguageToItalian() {
  strings.setLanguage('it');
  this.setState({});
}

It's also possible to set the language directly in your Xcode project using the following code snippet:

[[NSUserDefaults standardUserDefaults] setObject:[NSArray arrayWithObjects:@"de", nil] forKey:@"AppleLanguages"];

Replace de with a supported locale identifier to test.

Check out the WIKI page for additional informations.

Feel free to contact me on Twitter or open an issue.