1.在Project設置，加入中英兩種語言：

2.新建Localizable.strings文件，作為多語言相應的詞典，存儲多種語言，點擊右側Localization，勾選中英：

3.加入一個字段，

在English中，加入："SUBMIT_BTN_TITLE" = "Go";

在Chinese中，加入："SUBMIT_BTN_TITLE" = "開始";

//
//  GDLocalizableController.h
//  guide-book
//
//  Created by why on 7/16/14.
//  Copyright (c) 2014 why. All rights reserved.
//

#import <Foundation/Foundation.h>

@interface GDLocalizableController : NSObject

+(NSBundle *)bundle;//獲取當前資源文件

+(void)initUserLanguage;//初始化語言文件

+(NSString *)userLanguage;//獲取應用當前語言

+(void)setUserlanguage:(NSString *)language;//設置當前語言

@end






//
//  GDLocalizableController.m
//  guide-book
//
//  Created by why on 7/16/14.
//  Copyright (c) 2014 why. All rights reserved.
//

#import "GDLocalizableController.h"

@implementation GDLocalizableController

static NSBundle *bundle = nil;

+ ( NSBundle * )bundle{
    return bundle;
}
+(void)initUserLanguage{
    
    NSUserDefaults *def = [NSUserDefaults standardUserDefaults];
    NSString *string = [def valueForKey:@"userLanguage"];
    if(string.length == 0){
        //獲取系統當前語言版本號
        NSArray* languages = [def objectForKey:@"AppleLanguages"];
        NSString *current = [languages objectAtIndex:0];
        string = current;
        [def setValue:current forKey:@"userLanguage"];
        [def synchronize];//持久化。不加的話不會保存
    }
    
    //獲取文件路徑
    NSString *path = [[NSBundle mainBundle] pathForResource:string ofType:@"lproj"];
    bundle = [NSBundle bundleWithPath:path];//生成bundle
}

+(NSString *)userLanguage{
    
    NSUserDefaults *def = [NSUserDefaults standardUserDefaults];
    NSString *language = [def valueForKey:@"userLanguage"];
    return language;
}

+(void)setUserlanguage:(NSString *)language{
    
    NSUserDefaults *def = [NSUserDefaults standardUserDefaults];
    
    //1.第一步改變bundle的值
    NSString *path = [[NSBundle mainBundle] pathForResource:language ofType:@"lproj" ];
    bundle = [NSBundle bundleWithPath:path];
    
    //2.持久化
    [def setValue:language forKey:@"userLanguage"];
    [def synchronize];
}

@end

5. 自己定義一個宏方便處理：

// ----- 多語言設置
#define CHINESE @"zh-Hans"
#define ENGLISH @"en"
#define GDLocalizedString(key) [[GDLocalizableController bundle] localizedStringForKey:(key) value:@"" table:nil]

    [GDLocalizableController setUserlanguage:CHINESE];
    NSLog(GDLocalizedString(@"SUBMIT_BTN_TITLE"));
    [GDLocalizableController setUserlanguage:ENGLISH];
    NSLog(GDLocalizedString(@"SUBMIT_BTN_TITLE"));

參考資料：iOS 應用程序內部國際化，不尾隨系統語言

[iOS]怎樣在iOS開發中切換顯示語言實現國際化