[ios] How to force NSLocalizedString to use a specific language

On iPhone NSLocalizedString returns the string in the language of the iPhone. Is it possible to force NSLocalizedString to use a specific language to have the app in a different language than the device ?

I wanted to add support for a language that isn't officially supported by iOS (not listed in Language section under system settings). By following the Apple's Internationalization Tutorial and few hints here by Brian Webster and geon, I came up with this piece of code (put it in main.m):

int main(int argc, char * argv[]) {
    @autoreleasepool {
        // Grab regional settings locale, for Slovenian this is either sl_SI or en_SI
        NSLocale *locale = [NSLocale currentLocale];
        NSString *ll = [locale localeIdentifier]; // sl_SI

        // Grab the first part of language identifier
        NSArray *comp = [ll componentsSeparatedByString:@"_"];
        NSString *ll1 = @"en";
        if (comp.count > 0) {
            ll1 = comp[0]; // sl, en, ...
        }
        // Check if we already saved language (user can manually change it inside app for example)
        if (![[NSUserDefaults standardUserDefaults] objectForKey:@"SelectedLanguage"]) {
            //   Slovenian (Slovenia),            Slovenia
            if ([ll isEqualToString:@"sl_SI"] || [ll isEqualToString:@"en_SI"]) {
                ll1 = @"sl-SI"; // This is the part of localized path for Slovenian language that Xcode generates
            }
            // Add more unsupported languages here...

            [[NSUserDefaults standardUserDefaults] setObject:ll1 forKey:@"SelectedLanguage"]; // Save language
        }
        else {
            // Restore language as we have previously saved it
            ll1 = [[NSUserDefaults standardUserDefaults] objectForKey:@"SelectedLanguage"];
        }
        // Overwrite NSLocalizedString and StoryBoard language preference
        [[NSUserDefaults standardUserDefaults] setObject:[NSArray arrayWithObjects:ll1, @"en", @"fr", nil] forKey:@"AppleLanguages"];
        // Make sure settings are stored to disk
        [[NSUserDefaults standardUserDefaults] synchronize];

        return UIApplicationMain(argc, argv, nil, NSStringFromClass([AppDelegate class]));
    }
}

This works well for both Storyboard and NSLocalizedString code. The code assumes that user will have an option to manually change language inside app later on.

Of course, don't forget to add proper Storyboard translations and Localizable.strings translations (see link to Apple page above for how to do that).

I had the same problem recently and I didn't want to start and patch my entire NSLocalizedString nor force the app to restart for the new language to work. I wanted everything to work as-is.

My solution was to dynamically change the main bundle's class and load the appropriate bundle there:

Header file

@interface NSBundle (Language)
+(void)setLanguage:(NSString*)language;
@end

Implementation

#import <objc/runtime.h>

static const char _bundle=0;

@interface BundleEx : NSBundle
@end

@implementation BundleEx
-(NSString*)localizedStringForKey:(NSString *)key value:(NSString *)value table:(NSString *)tableName
{
    NSBundle* bundle=objc_getAssociatedObject(self, &_bundle);
    return bundle ? [bundle localizedStringForKey:key value:value table:tableName] : [super localizedStringForKey:key value:value table:tableName];
}
@end

@implementation NSBundle (Language)
+(void)setLanguage:(NSString*)language
{
    static dispatch_once_t onceToken;
    dispatch_once(&onceToken, ^
    {
        object_setClass([NSBundle mainBundle],[BundleEx class]);
    });
    objc_setAssociatedObject([NSBundle mainBundle], &_bundle, language ? [NSBundle bundleWithPath:[[NSBundle mainBundle] pathForResource:language ofType:@"lproj"]] : nil, OBJC_ASSOCIATION_RETAIN_NONATOMIC);
}
@end

So basically, when your app starts and before you load your first controller, simply call:

[NSBundle setLanguage:@"en"];

When your user changes his preferred language in your setting screen, simply call it again:

[NSBundle setLanguage:@"fr"];

To reset back to system defaults, simply pass nil:

[NSBundle setLanguage:nil];

Enjoy...

For those who need a Swift version:

var bundleKey: UInt8 = 0

class AnyLanguageBundle: Bundle {

    override func localizedString(forKey key: String,
                                  value: String?,
                                  table tableName: String?) -> String {

        guard let path = objc_getAssociatedObject(self, &bundleKey) as? String,
              let bundle = Bundle(path: path) else {

            return super.localizedString(forKey: key, value: value, table: tableName)
            }

        return bundle.localizedString(forKey: key, value: value, table: tableName)
    }
}

extension Bundle {

    class func setLanguage(_ language: String) {

        defer {

            object_setClass(Bundle.main, AnyLanguageBundle.self)
        }

        objc_setAssociatedObject(Bundle.main, &bundleKey,    Bundle.main.path(forResource: language, ofType: "lproj"), .OBJC_ASSOCIATION_RETAIN_NONATOMIC)
    }
}

As said earlier, just do:

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

But to avoid having to restart the app, put the line in the main method of main.m, just before UIApplicationMain(...).

I like best Mauro Delrio's method. I also have added the following in my Project_Prefix.pch

#import "Language.h"    
#define MyLocalizedString(key, alt) [Language get:key alter:alt]

So if you ever want to use the standard method (that uses NSLocalizedString) you can make a quick syntax substitution in all files.

Swift Version:

NSUserDefaults.standardUserDefaults().setObject(["fr"], forKey: "AppleLanguages")
NSUserDefaults.standardUserDefaults().synchronize()

In a nutshell :

Localize your application

It's the first thing you have to do is to localise your app with at least two languages (english and french in this example).

Override NSLocalizedString

In your code, instead of using NSLocalizedString(key, comment), use a macro MYLocalizedString(key, comment) defined like this : #define MYLocalizedString(key, comment) [[MYLocalizationSystem sharedInstance] localizedStringForKey:(key) value:(comment)];

This MYLocalizationSystem singleton will :

• Set langage by setting the right localized NSBundle user asks for
• Returns the localized NSString according to this previously set language

Set user language

When user changed application language in french, call [[MYLocalizationSystem sharedInstance] setLanguage:@"fr"];

- (void)setLanguage:(NSString *)lang
{
    NSString *path = [[NSBundle mainBundle] pathForResource:lang ofType:@"lproj"];
    if (!path)
    {
        _bundle = [NSBundle mainBundle];
        NSLog(@"Warning: No lproj for %@, system default set instead !", lang);
        return;
    }

    _bundle = [NSBundle bundleWithPath:path];
}

In this example this method set localized bundle to fr.lproj

Return localized string

Once you've set the localized bundle, you'll be able to get the right localised string from him with this method :

- (NSString *)localizedStringForKey:(NSString *)key value:(NSString *)value
{
    // bundle was initialized with [NSBundle mainBundle] as default and modified in setLanguage method
    return [self.bundle localizedStringForKey:key value:value table:nil];
}

Hope this will help you.

You'll find more details in this article from NSWinery.io

Here is a decent solution for this problem, and it does not require application restart.

https://github.com/cmaftuleac/BundleLocalization

This implementation works by tweaking inside NSBundle. The idea is that you override the method localizedStringForKey on the instance of NSBundle object, and then call this method on a different bundle with a different language. Simple and elegant fully compatible with all types of resources.

I usually do this in this way, but you MUST have all localization files in your project.

@implementation Language

static NSBundle *bundle = nil;

+(void)initialize 
{
    NSUserDefaults* defs = [NSUserDefaults standardUserDefaults];
    NSArray* languages = [defs objectForKey:@"AppleLanguages"];
    NSString *current = [[languages objectAtIndex:0] retain];
    [self setLanguage:current];
}

/*
  example calls:
    [Language setLanguage:@"it"];
    [Language setLanguage:@"de"];
*/
+(void)setLanguage:(NSString *)l
{
    NSLog(@"preferredLang: %@", l);
    NSString *path = [[ NSBundle mainBundle ] pathForResource:l ofType:@"lproj" ];
    bundle = [[NSBundle bundleWithPath:path] retain];
}

+(NSString *)get:(NSString *)key alter:(NSString *)alternate 
{
    return [bundle localizedStringForKey:key value:alternate table:nil];
}

@end

NSLocalizedString() reads the value for the key AppleLanguages from the standard user defaults ([NSUserDefaults standardUserDefaults]). It uses that value to choose an appropriate localization among all existing localizations at runtime. When Apple builds the user defaults dictionary at app launch, they look up the preferred language(s) key in the system preferences and copy the value from there. This also explains for example why changing the language settings in OS X has no effect on running apps, only on apps started thereafter. Once copied, the value is not updated just because the settings change. That's why iOS restarts all apps if you change then language.

However, all values of the user defaults dictionary can be overwritten by command line arguments. See NSUserDefaults documentation on the NSArgumentDomain. This even includes those values that are loaded from the app preferences (.plist) file. This is really good to know if you want to change a value just once for testing.

So if you want to change the language just for testing, you probably don't want to alter your code (if you forget to remove this code later on ...), instead tell Xcode to start your app with a command line parameters (e.g. use Spanish localization):

No need to touch your code at all. Just create different schemes for different languages and you can quickly start the app once in one language and once in another one by just switching the scheme.

This function will try to get localized string for current language and if it's not found it will get it using english language.

- (NSString*)L:(NSString*)key
{
    static NSString* valueNotFound = @"VALUE_NOT_FOUND";
    static NSBundle* enBundle = nil;

    NSString* pl = [NSLocale preferredLanguages][0];
    NSString* bp = [[NSBundle mainBundle] pathForResource:pl ofType:@"lproj"];
    NSBundle* b = [NSBundle bundleWithPath:bp];

    NSString* s = [b localizedStringForKey:key value:valueNotFound table:nil];
    if ( [s isEqualToString:valueNotFound] ) {
        if ( !enBundle ) {
            bp = [[NSBundle mainBundle] pathForResource:@"en" ofType:@"lproj"];
            enBundle = [NSBundle bundleWithPath:bp];
        }
        s = [enBundle localizedStringForKey:key value:key table:nil];
    }

    return s;
}

You could build a sub-bundle with the set of localized strings that you want to do this with, and then use NSLocalizedStringFromTableInBundle() to load them. (I'm assuming that this is content separate from the normal UI localization you might be doing on the app.)

In file .pch to define:

#define currentLanguageBundle [NSBundle bundleWithPath:[[NSBundle mainBundle] pathForResource:[[NSLocale preferredLanguages] objectAtIndex:0] ofType:@"lproj"]]


#define NSLocalizedString(str,nil) NSLocalizedStringFromTableInBundle(str, nil, currentLanguageBundle, @"")

Maybe you should complement with this (on .pch file after #import ):

extern NSBundle* bundle; // Declared on Language.m

#ifdef NSLocalizedString
    #undef NSLocalizedString
    // Delete this line to avoid warning
    #warning "Undefining NSLocalizedString"
#endif

#define NSLocalizedString(key, comment) \
    [bundle localizedStringForKey:(key) value:@"" table:nil]

You can do something like this:

NSString *bundlePath = [[NSBundle mainBundle] pathForResource:@"Localizable" ofType:@"strings" inDirectory:nil forLocalization:@"es"];


NSBundle *spanishBundle = [[NSBundle alloc] initWithPath:[bundlePath stringByDeletingLastPathComponent]];

NSLocalizedStringFromTableInBundle(@"House", nil, spanishBundle, nil):

whatever you all do, the best way is to take the short_name for the specified language, i.e.: fr, en, nl, de, it, etc... and assign the same to a global value.

make a picker view to pop up like a drop down menu (combination of a button on click of which a picker view appears from below with a list of languages) and select the language you desire. let the short name be stored internally. make a .h + .m file named LocalisedString.

Set the global value of short_name to be equal to the obtained value in LocalisedString.m When the required language is selected assign the NSBundlePath to create project sub-directories for the needed language. for eg, nl.proj, en.proj.

When the particular proj folder is selected call the localised string for the respective language and change the language dynamically.

no rules broken.

Swift 3 solution:

let languages = ["bs", "zh-Hant", "en", "fi", "ko", "lv", "ms", "pl", "pt-BR", "ru", "sr-Latn", "sk", "es", "tr"]
UserDefaults.standard.set([languages[0]], forKey: "AppleLanguages")

Gave some examples of language codes that can be used. Hope this helps

As Brian Webster mentions, the language needs to be set "sometime early in your application's startup". I thought applicationDidFinishLaunching: of the AppDelegate should be a suitable place to do it, since it's where I do all other initialization.

But as William Denniss mentions, that seems to have an effect only after the app is restarted, which is kind of useless.

It seems to work fine if I put the code in the main function, though:

int main(int argc, char *argv[]) {
    NSAutoreleasePool * pool = [[NSAutoreleasePool alloc] init];

    // Force language to Swedish.
    [[NSUserDefaults standardUserDefaults]
     setObject:[NSArray arrayWithObject:@"sv"]
     forKey:@"AppleLanguages"];

    int retVal = UIApplicationMain(argc, argv, nil, nil);
    [pool release];
    return retVal;
}

I'd appreciate any comments on this.

Based on Tudorizer's answer to change language without leaving or restarting the application.

Instead of a macro, use a class for accessing the preferred language in order to check if a specific language code is present.

Below is a class used to obtain the current language bundle that is working for iOS 9:

@implementation OSLocalization

+ (NSBundle *)currentLanguageBundle
{
    // Default language incase an unsupported language is found
    NSString *language = @"en";

    if ([NSLocale preferredLanguages].count) {
        // Check first object to be of type "en","es" etc
        // Codes seen by my eyes: "en-US","en","es-US","es" etc

        NSString *letterCode = [[NSLocale preferredLanguages] objectAtIndex:0];

        if ([letterCode rangeOfString:@"en"].location != NSNotFound) {
            // English
            language = @"en";
        } else if ([letterCode rangeOfString:@"es"].location != NSNotFound) {
            // Spanish
            language = @"es";
        } else if ([letterCode rangeOfString:@"fr"].location != NSNotFound) {
            // French
            language = @"fr";
        } // Add more if needed
    }

    return [NSBundle bundleWithPath:[[NSBundle mainBundle] pathForResource:language ofType:@"lproj"]];
}

/// Check if preferred language is English
+ (BOOL)isCurrentLanguageEnglish
{
    if (![NSLocale preferredLanguages].count) {
        // Just incase check for no items in array
        return YES;
    }

    if ([[[NSLocale preferredLanguages] objectAtIndex:0] rangeOfString:@"en"].location == NSNotFound) {
        // No letter code for english found
        return NO;
    } else {
        // Tis English
        return YES;
    }
}

/*  Swap language between English & Spanish
 *  Could send a string argument to directly pass the new language
 */
+ (void)changeCurrentLanguage
{
    if ([self isCurrentLanguageEnglish]) {
        [[NSUserDefaults standardUserDefaults] setObject:@[@"es"] forKey:@"AppleLanguages"];
    } else {
        [[NSUserDefaults standardUserDefaults] setObject:@[@"en"] forKey:@"AppleLanguages"];
    }
}
@end

Use the class above to reference a string file / image / video / etc:

// Access a localized image
[[OSLocalization currentLanguageBundle] pathForResource:@"my_image_name.png" ofType:nil]
// Access  a localized string from Localizable.strings file
NSLocalizedStringFromTableInBundle(@"StringKey", nil, [OSLocalization currentLanguageBundle], @"comment")

Change language in-line like below or update the "changeCurrentLanguage" method in the class above to take a string parameter referencing the new language.

[[NSUserDefaults standardUserDefaults] setObject:@[@"es"] forKey:@"AppleLanguages"];

Swift 3 extensions:

extension Locale {
    static var preferredLanguage: String {
        get {
            return self.preferredLanguages.first ?? "en"
        }
        set {
            UserDefaults.standard.set([newValue], forKey: "AppleLanguages")
            UserDefaults.standard.synchronize()
        }
    }
}

extension String {
    var localized: String {

    var result: String

    let languageCode = Locale.preferredLanguage //en-US

    var path = Bundle.main.path(forResource: languageCode, ofType: "lproj")

    if path == nil, let hyphenRange = languageCode.range(of: "-") {
        let languageCodeShort = languageCode.substring(to: hyphenRange.lowerBound) // en
        path = Bundle.main.path(forResource: languageCodeShort, ofType: "lproj")
    }

    if let path = path, let locBundle = Bundle(path: path) {
        result = locBundle.localizedString(forKey: self, value: nil, table: nil)
    } else {
        result = NSLocalizedString(self, comment: "")
    }
        return result
    }
}

Usage:

Locale.preferredLanguage = "uk"

label.text = "localizedKey".localized

What do you think about this solution for Swift 3?

extension String {

    func localized(forLanguage language: String = Locale.preferredLanguages.first!.components(separatedBy: "-").first!) -> String {

        guard let path = Bundle.main.path(forResource: language == "en" ? "Base" : language, ofType: "lproj") else {

            let basePath = Bundle.main.path(forResource: "Base", ofType: "lproj")!

            return Bundle(path: basePath)!.localizedString(forKey: self, value: "", table: nil)
        }

        return Bundle(path: path)!.localizedString(forKey: self, value: "", table: nil)
    }
}

Simple usage:

"report".localized(forLanguage: "pl") //forced language
"report".localized() //default language selected by user in settings, in case when your app doesnt support selected lanaguage, the default one is selected, here is an english.

For Swift you can override the main.swift file and set the UserDefaults string there before you app runs. This way you do not have to restart the App to see the desired effect.

import Foundation
import UIKit

// Your initialisation code here
let langCultureCode: String = "LANGUAGE_CODE"

UserDefaults.standard.set([langCultureCode], forKey: "AppleLanguages")
UserDefaults.standard.synchronize()

UIApplicationMain(CommandLine.argc, CommandLine.unsafeArgv, nil, NSStringFromClass(AppDelegate.self))

paired together with the removal of @UIApplicationMain in your AppDelegate.swift file.

I came up with a solution that allows you to use NSLocalizedString. I create a category of NSBundle call NSBundle+RunTimeLanguage. The interface is like this.

// NSBundle+RunTimeLanguage.h
#import <Foundation/Foundation.h>
@interface NSBundle (RunTimeLanguage)
#define NSLocalizedString(key, comment) [[NSBundle mainBundle] runTimeLocalizedStringForKey:(key) value:@"" table:nil]
- (NSString *)runTimeLocalizedStringForKey:(NSString *)key value:(NSString *)value table:(NSString *)tableName;
@end

The implementation is like this.

// NSBundle+RunTimeLanguage.m
#import "NSBundle+RunTimeLanguage.h"
#import "AppDelegate.h"

@implementation NSBundle (RunTimeLanguage)

- (NSString *)runTimeLocalizedStringForKey:(NSString *)key value:(NSString *)value table:(NSString *)tableName
{
    AppDelegate *appDelegate = (AppDelegate *)[UIApplication sharedApplication].delegate;
    NSString *path= [[NSBundle mainBundle] pathForResource:[appDelegate languageCode] ofType:@"lproj"];
    NSBundle *languageBundle = [NSBundle bundleWithPath:path];
    NSString *localizedString=[languageBundle localizedStringForKey:key value:key table:nil];
    return localizedString;
}
@end

Than just add import NSBundle+RunTimeLanguage.h into the files that use NSLocalizedString.

As you can see I store my languageCode in a property of AppDelegate. This could be stored anywhere you'd like.

This only thing I don't like about it is a Warning that NSLocalizedString marco redefined. Perhaps someone could help me fix this part.

The trick to use specific language by selecting it from the app is to force the NSLocalizedString to use specific bundle depending on the selected language ,

here is the post i have written for this learning advance localization in ios apps

and here is the code of one sample app advance localization in ios apps

Do not use on iOS 9. This returns nil for all strings passed through it.

I have found another solution that allows you to update the language strings, w/o restarting the app and compatible with genstrings:

Put this macro in the Prefix.pch:

#define currentLanguageBundle [NSBundle bundleWithPath:[[NSBundle mainBundle] pathForResource:[[NSLocale preferredLanguages] objectAtIndex:0] ofType:@"lproj"]]

and where ever you need a localized string use:

NSLocalizedStringFromTableInBundle(@"GalleryTitleKey", nil, currentLanguageBundle, @"")

To set the language use:

[[NSUserDefaults standardUserDefaults] setObject:[NSArray arrayWithObject:@"de"] forKey:@"AppleLanguages"];

Works even with consecutive language hopping like:

NSLog(@"test %@", NSLocalizedStringFromTableInBundle(@"NewKey", nil, currentLanguageBundle, @""));
[[NSUserDefaults standardUserDefaults] setObject:[NSArray arrayWithObject:@"fr"] forKey:@"AppleLanguages"];
NSLog(@"test %@", NSLocalizedStringFromTableInBundle(@"NewKey", nil, currentLanguageBundle, @""));
[[NSUserDefaults standardUserDefaults] setObject:[NSArray arrayWithObject:@"it"] forKey:@"AppleLanguages"];
NSLog(@"test %@", NSLocalizedStringFromTableInBundle(@"NewKey", nil, currentLanguageBundle, @""));
[[NSUserDefaults standardUserDefaults] setObject:[NSArray arrayWithObject:@"de"] forKey:@"AppleLanguages"];
NSLog(@"test %@", NSLocalizedStringFromTableInBundle(@"NewKey", nil, currentLanguageBundle, @""));

In swift 4, I have solved it without needing to restart or use libraries.

After trying many options, I found this function, where you pass the stringToLocalize (of Localizable.String, the strings file) that you want to translate, and the language in which you want to translate it, and what it returns is the value for that String that you have in Strings file:

    func localizeString (stringToLocalize: String, language: String) -> String
    {
        let path = Bundle.main.path (forResource: language, ofType: "lproj")
        let languageBundle = Bundle (path: path!)
        return languageBundle! .localizedString (forKey: stringToLocalize, value: "", table: nil)
    }

Taking into account this function, I created this function in a Swift file:

struct CustomLanguage {

    func createBundlePath () -> Bundle {
        let selectedLanguage = //recover the language chosen by the user (in my case, from UserDefaults)
        let path = Bundle.main.path(forResource: selectedLanguage, ofType: "lproj")
        return Bundle(path: path!)!
    }
}

To access from the whole app, and in each string of the rest of ViewControllers, instead of putting:

NSLocalizedString ("StringToLocalize", comment: “")

I have replaced it with

let customLang = CustomLanguage() //declare at top
let bundleLanguage = customLang.createBundle()

NSLocalizedString("StringToLocalize", tableName: nil, bundle: bundleLanguage, value: "", comment: “”) //use in each String

I do not know if it's the best way, but I found it very simple, and it works for me, I hope it helps you!

for my case i have two localized file , ja and en

and i would like to force it to en if the preferred language in the system neither en or ja

i'm going to edit the main.m file

i 'll check whether the first preferred is en or ja , if not then i 'll change the second preferred language to en.

int main(int argc, char *argv[])
{

    [[NSUserDefaults standardUserDefaults] removeObjectForKey:@"AppleLanguages"];
    [[NSUserDefaults standardUserDefaults] synchronize];

    NSString *lang = [[NSLocale preferredLanguages] objectAtIndex:0];

    if (![lang isEqualToString:@"en"]  &&  ![lang isEqualToString:@"ja"]){

        NSMutableArray *array = [[NSMutableArray alloc] initWithArray:[NSLocale preferredLanguages]];
        [array replaceObjectAtIndex:1 withObject:@"en"];

        [[NSUserDefaults standardUserDefaults] setObject:array forKey:@"AppleLanguages"];
        [[NSUserDefaults standardUserDefaults] synchronize];


    }

    @autoreleasepool {
        return UIApplicationMain(argc, argv, nil, NSStringFromClass([AppDelegate class]));


    }


}