Why language change required app to restart in Objective C

Question

I am new in iOS and I am facing problem in language conversion

For English I am using code like this

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

            //to set the selected language at runtime (dynamically)
            NSLog(@"Language set=Malay");
            [NSBundle setLanguage:@"en"];
            MenuScreen *menu=[[MenuScreen alloc] initWithNibName:@"MenuScreen" bundle:nil];
            [self.navigationController pushViewController:menu animated:YES];

For Thai Language I used code like this

[[NSUserDefaults standardUserDefaults] setObject:[NSArray arrayWithObjects:@"th-TH", nil] forKey:@"AppleLanguages"];
            [[NSUserDefaults standardUserDefaults]synchronize];

            //to set the selected language at runtime (dynamically)
            NSLog(@"Language set=Malay");
            [NSBundle setLanguage:@"th-TH"];
            MenuScreen *menu=[[MenuScreen alloc] initWithNibName:@"MenuScreen" bundle:nil];
            [self.navigationController pushViewController:menu animated:YES];

But every time it required to restart app. Is there is any solution for this or any thing I am doing wrong. Thanks in Advance!

Answer 1

Muju I created sample project and I worked getting solution for your question.I got the solution perfectly.

In my below sample I want to change "Welcome to Thailand" to "ยินดีต้อนรับสู่ประเทศไทย".I use localization concept for this.

Before going to steps, I want you to see my storyboard designing

Please follow the below steps.

STEP 1:Click Project->info->Localization->Click +

Now it shows the drop down list of Language.From that we should select Thai

STEP 2:Once we choose or select the Language from drop down list,it shows the below window and we need to click Finish button

Now it looks like below

STEP 3:Create the String File for the localization and set the name.

above I set String file name as LocalizationThai

STEP 4:Click the LocalizationThai.strings also click the File Inspector.Click the Localization inside the File Inspector.Now it shows the below pop up box.

STEP 5:Click Localize.Once you Localize,it shows below like this

STEP 6:Click 3 Checkboxes

Now in bundle we have 3 files under LocalizationThai.strings

STEP 7:Write your required changing text in string files.

i.In LocalizationThai.strings(Thai) file I write below text

ii.In LocalizationThai.strings(English) file I write below text

iii.In LocalizationThai.strings(Base) file I write below text

STEP 8:Create the Header File for the multiple Languages.

STEP 9 : set the Header name(I set header name as LocalizationHeader) and define Languages in the Header file like below

LocalizationHeader.h

#ifndef LocalizationHeader_h
#define LocalizationHeader_h


#define ENGLISH 0
#define THAI 1


#endif /* LocalizationHeader_h */

STEP 10:Implement the below coding part

Localization.h

#import <Foundation/Foundation.h>
#import "LocalizationHeader.h"
@interface Localization : NSObject
+(Localization *)sharedInstance;
+(NSString*) strSelectLanguage:(int)curLang;
+(NSString*) languageSelectedStringForKey:(NSString*) key;
@end

Localization.m

#import "Localization.h"
int currentLanguage,selectedrow;
@implementation Localization

+(Localization *)sharedInstance
{
    static Localization *sharedInstance = nil;
    static dispatch_once_t onceToken;
    dispatch_once(&onceToken, ^{
        sharedInstance = [[Localization alloc] init];
    });
    return sharedInstance;
}


+(NSString*) strSelectLanguage:(int)curLang{
    if(curLang==THAI){
        [[NSUserDefaults standardUserDefaults] setObject:[NSArray arrayWithObjects:@"th", nil]forKey:@"AppleLanguages"];
    }
    else{
        [[NSUserDefaults standardUserDefaults] setObject:[NSArray arrayWithObjects:@"en", nil]forKey:@"AppleLanguages"];
    }
    [[NSUserDefaults standardUserDefaults] synchronize];
    currentLanguage=curLang;
    NSString *strLangSelect = [[[NSUserDefaults standardUserDefaults]objectForKey:@"AppleLanguages"] objectAtIndex:0];
    return strLangSelect;
}

+(NSString*) languageSelectedStringForKey:(NSString*) key
{
    NSString *path;
    NSString *strSelectedLanguage = [[[NSUserDefaults standardUserDefaults]objectForKey:@"AppleLanguages"] objectAtIndex:0];
    //When we check with iPhone,iPad device it shows "en-US".So we need to change it to "en"
    if([strSelectedLanguage hasPrefix:@"en-"])
        strSelectedLanguage = [strSelectedLanguage stringByReplacingOccurrencesOfString:@"en-US" withString:@"en"];
    if([strSelectedLanguage isEqualToString:[NSString stringWithFormat: @"en"]]){
        currentLanguage=ENGLISH;
        selectedrow=ENGLISH;
        path = [[NSBundle mainBundle] pathForResource:@"en" ofType:@"lproj"];
    }
    else{
        currentLanguage=THAI;
        selectedrow=THAI;
        path = [[NSBundle mainBundle] pathForResource:@"th" ofType:@"lproj"];
    }
    NSBundle* languageBundle = [NSBundle bundleWithPath:path];
    NSString* str=[languageBundle localizedStringForKey:key value:@"" table:@"LocalizationThai"];
    return str;
}
@end

ViewController.h

#import <UIKit/UIKit.h>
#import "Localization.h"
@interface ViewController : UIViewController{
    Localization *localization;

}
@property (strong, nonatomic) IBOutlet UILabel *lblWelcome;
- (IBAction)actionChangeLanToThai:(id)sender;
- (IBAction)actionChangeLangToEng:(id)sender;
@end

ViewController.m

#import "ViewController.h"
@interface ViewController ()
@end
@implementation ViewController
@synthesize lblWelcome;

- (void)viewDidLoad {
    [super viewDidLoad];
    // Do any additional setup after loading the view, typically from a nib.

    localization = [Localization sharedInstance];
    lblWelcome.text = [Localization languageSelectedStringForKey:@"Welcome to Thailand"];
}

- (void)didReceiveMemoryWarning {
    [super didReceiveMemoryWarning];
    // Dispose of any resources that can be recreated.
}

- (IBAction)actionChangeLanToThai:(id)sender {
    [Localization strSelectLanguage:THAI];
    lblWelcome.text = [Localization languageSelectedStringForKey:@"Welcome to Thailand"];

}

- (IBAction)actionChangeLangToEng:(id)sender {
    [Localization strSelectLanguage:ENGLISH];
    lblWelcome.text = [Localization languageSelectedStringForKey:@"Welcome to Thailand"];
}
@end

When I run the app first

Then When I change the Language from English to Thai

Again when I change it to English

You have to follow the same steps for XIB

Below is for XIB

I create the ViewController with XIB.ViewController name is RootViewController

Now see the designing part

AppDelegate.h

#import <UIKit/UIKit.h>
#import "RootViewController.h"
@interface AppDelegate : UIResponder <UIApplicationDelegate>
@property (strong, nonatomic) UIWindow *window;
@property (strong,nonatomic) RootViewController *viewController;
@end

AppDelegate.m

- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions {
    self.window = [[UIWindow alloc] initWithFrame:[[UIScreen mainScreen] bounds]];
    self.viewController = [[RootViewController alloc] initWithNibName:@"RootViewController" bundle:nil];
    UINavigationController *navController = [[UINavigationController alloc] initWithRootViewController:self.viewController];
    self.window.rootViewController = navController;
    [navController setNavigationBarHidden:YES];
    [self.window makeKeyAndVisible];
    return YES;     
  }

RootViewController.h

 #import <UIKit/UIKit.h>
 #import "Localization.h"
 @interface RootViewController : UIViewController{
    Localization *localization;
 }
 @property (strong, nonatomic) IBOutlet UILabel *lblWelcomeThaiLang;
 - (IBAction)actionChangeLangToThai:(id)sender;
 - (IBAction)actionChangeLangToEng:(id)sender;
 @end

RootViewController.m

 #import "RootViewController.h"
 @interface RootViewController ()
 @end
 @implementation RootViewController
 @synthesize lblWelcomeThaiLang;
 - (void)viewDidLoad {
    [super viewDidLoad];
    // Do any additional setup after loading the view from its nib.
 }
 - (void)didReceiveMemoryWarning {
    [super didReceiveMemoryWarning];
    // Dispose of any resources that can be recreated.
 }
 - (IBAction)actionChangeLangToThai:(id)sender {
    [Localization strSelectLanguage:THAI];
    lblWelcomeThaiLang.text = [Localization languageSelectedStringForKey:@"Welcome to Thailand"];
 }
 - (IBAction)actionChangeLangToEng:(id)sender {
    [Localization strSelectLanguage:ENGLISH];
    lblWelcomeThaiLang.text = [Localization languageSelectedStringForKey:@"Welcome to Thailand"];
 }
 @end

Now see the result