If you want to add new langauge, you have to follow some few steps:

Step 1

First open Project_HOME > assets > localization, simply make a copy of English localization and rename it as YOUR-LANGUAGE-CODE_localization.json then translate the right side of sentences in your language. IMPORTANT Your file name must be contain language code like YOUR-LANGUAGE-CODE_localization.json (e.g en_localization.json)

Step 2

You need to add the new files path in pubspec.yaml, so it can be bundled in final app binary after compile. Open file Project_HOME > pubspec.yaml and find the assets section. Copy your localized strings file name and mention it like following example.

assets:
  ...
    - assets/localization/en_localization.json
    - assets/localization/YOUR-LANGUAGE-CODE_localization.json
  ...

Step 3

Now go to Project_HOME > lib > hooks_v2.dart and look for the getLanguageCodeAndName() method. Specify your language code and language name here e.g:

  …
  static getLanguageCodeAndName() {
    LanguageHook languageHook = () {

      Map<String,dynamic> russianLanguageMap = {
        "languageName": "Russian",          
        "languageCode": "ru"                
      };

      Map<String,dynamic> yourLanguageMap = {
        "languageName": "YOUR-LANGUAGE-NAME",      // Specify your language name
        "languageCode": "YOUR-LANGUAGE-CODE"       // Specify your language code
      };

      List<dynamic> languageList = [russianLanguageMap, yourLanguageMap];  //add your map here
      return languageList;
    };

    return languageHook;
  }
  …

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