How to Localize a Mobile App into Multiple Languages

The essentials

Localization is not translating a finished app at the end of a project; it is an architectural decision. If every text lives in resources from day one and dates, numbers and currencies are formatted per locale, adding a language becomes a translator's job, not a redesign.

Where to keep strings

Rules that apply everywhere:

• Keys describe meaning, not text: checkout_pay_button, not button_text_1.
• Do not build sentences from fragments: word order differs between languages. Use placeholders: "Order %1$s has been delivered".
• Add a translator comment: where the string appears and how much room it has.
• Do not put text in images.

Plurals

Russian nouns after a number take three forms: "1 товар", "2 товара", "5 товаров". English has two. In Uzbek the noun stays singular after a numeral: "5 ta mahsulot". So never write if (n == 1) logic — use system rules.

Android:

<plurals name="items_count">
    <item quantity="one">%d item</item>
    <item quantity="other">%d items</item>
</plurals>

Flutter (ARB):

{
  "itemsCount": "{count, plural, one{{count} item} other{{count} items}}",
  "@itemsCount": {
    "placeholders": { "count": { "type": "int" } }
  }
}

Each language file lists only the categories that language needs; Russian, for example, uses one, few, many and other.

Uzbek: Latin and Cyrillic

The official script is Latin, but part of the audience, especially older users, is used to Cyrillic. Decide early whether you need both.

• Locale codes: uz (Latin by default) and uz-Cyrl for Cyrillic. On Android the Cyrillic folder is values-b+uz+Cyrl; in Flutter, a file like app_uz_Cyrl.arb.
• Apostrophes: correct Latin spelling uses o‘, g‘ and ’ (tutuq belgisi), not a plain '. A plain apostrophe breaks search and looks careless.
• Automatic transliteration makes mistakes on loanwords. The Cyrillic version still needs proofreading.
• System components: not every framework ships translations of built-in dialogs and date pickers for uz-Cyrl. Check what appears instead.
• String length: Uzbek and Russian texts are usually longer than English. Design buttons with room to spare.

RTL basics

If Arabic, Persian or Hebrew are on the roadmap, the interface must mirror right to left:

• use leading/trailing and start/end instead of left/right;
• on Android set android:supportsRtl="true"; in Flutter use EdgeInsetsDirectional;
• mirror directional icons (back arrows) but not logos or media controls;
• test layouts with pseudo-languages: Xcode offers Right-to-Left and Double-Length Pseudolanguage, Android has pseudolocales.

Switching language inside the app

• Android: since Android 13 the system offers a per-app language setting. AppCompatDelegate.setApplicationLocales() lets you change language on older versions too. List the languages in locales_config.
• iOS: users choose the app's language in the system Settings app, and you can open that screen from the app. A custom switcher without restart needs your own string loading and is a frequent source of bugs.
• Flutter: change the locale of MaterialApp and persist the choice locally.

Take the default language from the system, not from location: many people in Uzbekistan use their phones in Russian.

Localizing the store listing

• Translate the name, subtitle, description, keywords and screenshots — screenshots are what people see first.
• Research keywords for how people search in each language instead of translating them literally.
• The App Store and Google Play support different sets of listing languages. If a language is missing, carry the key message in screenshot captions.
• Make sure listing languages match the languages the app actually supports.