--- title: "Localization: Change languages in iOS PDF viewer | Nutrient" canonical_url: "https://www.nutrient.io/guides/ios/features/localization/" md_url: "https://www.nutrient.io/guides/ios/features/localization.md" last_updated: "2026-05-25T16:07:03.523Z" description: "Localization: Change languages in iOS PDF viewer | guide for Nutrient iOS SDK with detailed instructions and code examples." --- # Localization: Change languages in our iOS PDF viewer Nutrient iOS SDK comes with many built-in languages: - Arabic (ar) ([including R2L interface support](https://www.nutrient.io/blog/pspdfkit-ios-6-4/)) - Chinese Simplified / Chinese Traditional (zh-Hans/zh-Hant) - Croatian (hr) - Czech (cs) - Danish (da) - Dutch (nl) - English (en) - English United Kingdom (en-GB) - Finnish (fi) - French (fr) - French Canada (fr-CA) - German (de) - Greek (el) - Hebrew (he) - Indonesian (id) - Italian (it) - Japanese (ja) - Korean (ko) - Malay (ms) - Norwegian Bokmål (nb-NO) - Polish (pl) - Portuguese Brazil / Portugal (pt-BR/pt-PT) - Russian (ru) - Slovak (sk) - Slovenian (sl) - Spanish (es) - Swedish (sv) - Thai (th) - Turkish (tr) - Ukrainian (uk) - Welsh (cy) These languages are used automatically depending on the preferred language. To enable a language, your application must also be localized in that language — otherwise, Nutrient will fall back to English (the reason being that you would otherwise end up with a partially translated app, which isn’t a good user experience). To translate your app, follow [Apple’s localization guidelines](https://developer.apple.com/library/archive/documentation/MacOSX/Conceptual/BPInternational/LocalizingYourApp/LocalizingYourApp.html#//apple_ref/doc/uid/10000171i-CH5-SW1) and provide your `.strings` file in all the languages you want to support. You can also use Nutrient’s [`setLocalizationDictionary(_:)`](https://www.nutrient.io/api/ios/documentation/pspdfkit/setlocalizationdictionary(_:)) or [`setLocalizationClosure(_:)`](https://www.nutrient.io/api/ios/documentation/pspdfkit/setlocalizationclosure(_:)) to customize the localization. iTunes Connect doesn’t support all of these languages. However, iOS devices can still be set to these languages. Just be aware that there’s no localized storefront. See [here](http://kitefaster.com/2016/03/09/itunes-connect-api-app-store-and-corresponding-xcode-language-codes/) for a detailed list of Xcode language codes. ## Adding additional localization to Nutrient You can add additional localization by adding the corresponding folders or setting a new localization programmatically. To see all strings that should be localized, look inside `PSPDFKit/PSPDFKit.bundle/en.lproj/PSPDFKit.strings`. Nutrient uses `NSLocale.preferredLanguages` to determine a language and falls back to English if this method doesn’t return anything or the language isn’t available either in the `PSPDFKit.bundle` or the language dictionary. Nutrient won’t look into your default project strings file. To get all strings translated (including OS-level default buttons like Edit or Done), you need to add a `Localizable.strings` file of your target language to your project: ### SWIFT ```swift setLocalizationDictionary([ "en": [ "Go to %@": "Browse %@", "%d of %d": "Page %d of %d" ] ]) ``` ### OBJECTIVE-C ```objc PSPDFSetLocalizationDictionary(@{ @"en": @{ @"Go to %@": @"Browse %@", @"%d of %d": @"Page %d of %d" } }); ``` You can also use `setLocalizationClosure(_:)` to register a block that’s called every time a string is translated. In this way, you can easily use your default bundle or a custom bundle with `NSLocalizedStringFromTableInBundle`: ### SWIFT ```swift setLocalizationClosure { stringToLocalize in guard let stringToLocalize = stringToLocalize else { return nil } // This will look up strings in `language/PSPDFKit.strings` inside your resource folder. return NSLocalizedString(stringToLocalize, tableName: "PSPDFKit", comment: "") // You can also route translation through your default localization: return NSLocalizedString(stringToLocalize, comment: "") // Or use a custom variant, for example, to test if everything is localized. // Keep in mind that several strings, like Edit, are provided by the system and are automatically translated, so long as you have the correct localization resources set. return String(format: "_____%@_____", arguments: [stringToLocalize]) } ``` ### OBJECTIVE-C ```objc PSPDFSetLocalizationBlock(^NSString *(NSString *stringToLocalize) { // This will look up strings in `language/PSPDFKit.strings` inside your resource folder. return NSLocalizedStringFromTable(stringToLocalize, @"PSPDFKit", nil); // You can also route translation through your default localization: return NSLocalizedString(stringToLocalize, nil); // Or use a custom variant, for example, to test if everything is localized. // Keep in mind that several strings, like Edit, are provided by the system and are automatically translated, so long as you have the correct localization resources set. return [NSString stringWithFormat:@"_____%@_____", stringToLocalize]; }); ``` ## Pluralization considerations Nutrient uses both the `PSPDFKit.strings` file and the `PSPDFKit.stringsdict` file. A [`.stringsdict` file](https://developer.apple.com/library/ios/documentation/MacOSX/Conceptual/BPInternational/StringsdictFileFormat/StringsdictFileFormat.html) is used to define language pluralization rules, as some languages have more pluralization variants besides one and many; for example, see the pluralization rule for Croatian: ```xml %tu match(es) found NSStringLocalizedFormatKey %#@tu_matches_found@ tu_matches_found NSStringFormatSpecTypeKey NSStringPluralRuleType NSStringFormatValueTypeKey tu zero Nema pronađenih rezultata one %tu pronađen rezultat two %tu pronađena rezultata other %tu pronađenih rezultata ``` `PSPDFLocalize()` automatically looks in both the `stringsdict` and the classical `strings` files to look up localized strings. ## Forcing a specific language You can manually override system defaults and force a specific language. We generally don’t recommend this, as it’s against Apple HIG. If you have a use case that requires this, recreate all UI elements manually after updating the setting or — ideally — simply restart the application to update the localization. You can achieve this by either setting [`setLocalizationClosure(_:)`](https://www.nutrient.io/api/ios/documentation/pspdfkit/setlocalizationclosure(_:)) and returning a custom language, or (better) changing this systemwide via setting the `AppleLanguages` in the user defaults. This needs to happen early, before your app initializes. You can place this in the `main.m/Main.swift` file before `UIApplicationMain` or simply use a function with a constructor attribute in an Objective-C file: ```objc __attribute__((constructor)) static void PSCForceCustomLanguage(void) { [NSUserDefaults.standardUserDefaults setObject:@[@"de"] forKey:@"AppleLanguages"]; } ``` [See how this can be done in Swift here](http://stackoverflow.com/a/38429383/83160). You can learn more about `AppleLanguages` in [Apple’s QA1391 article](https://developer.apple.com/library/content/qa/qa1391/_index.html). If your app requires updating localization at runtime without restarting the app, you can do more advanced tricks like [swizzling NSBundle’s `localizedString(forKey:value:table:)`](https://www.factorialcomplexity.com/blog/how-to-change-localization-internally-in-your-ios-application). --- ## Related pages - [Customizing PDF viewer styling on iOS](/guides/ios/customizing-the-interface/appearance-styling.md) - [Editing PDFs in our iOS viewer](/guides/ios/features/document-editor-ui.md) - [Customizing our iOS PDF viewer](/guides/ios/user-interface.md) - [Overriding classes in our iOS viewer](/guides/ios/getting-started/overriding-classes.md) - [Customize electronic signatures UI on iOS](/guides/ios/signatures/customizing-the-signature-user-interface.md) - [Customizing the toolbar in our iOS PDF viewer](/guides/ios/user-interface/main-toolbar.md) - [Customizing the toolbar in our visionOS PDF viewer](/guides/ios/user-interface/main-toolbar-visionos.md) - [Customizing menus on iOS](/guides/ios/customizing-the-interface/customizing-menus.md)