iOS开发APP内部实现点击按钮切换语言

本文主要针对APP国际化进行操作，使APP内部控件显示语言可以不随系统语言做改变，自由切换.

效果如下：

Language.gif

核心方法：

    NSLocalizedStringFromTable(<#key#>, <#tbl#>, <#comment#>)

原理即在工程内部建立 .String，在内部采用键值对方式对所需要切换语言的文字进行赋值

1.工程内部创建.String文件，命名为Language.String

1.png

2.右侧菜单栏点击Localize，弹出菜单选择English，确定

2.png

3.png

3.第二步结束后选择工程，选择PROJECT，下方Localizations菜单中点击+号选择添加中文

4.png

4.此时Language.String中会显示两个文件，Language.String(Chinese) 和 Language.String(English)，这一步像这两个文件中添加键值对

5.png

英文文件中：

"denglu" = "Login";
"account" = "Phone number/email address";
"password" = "Password";
"verification" = "Verification code";
"message" = "SMS verification code";
"forget" = "Forget?";
"newregist" = "Registration";
"question" = "Problems";

中文文件中

"denglu" = "登录";
"account" = "请输入手机号/邮箱";
"password" = "请输入登录密码";
"verification" = "请输入验证码";
"message" = "通过短信验证码登录";
"forget" = "忘记密码？";
"newregist" = "新用户注册";
"question" = "常见问题";

5.新建一个单例类，ChangeLanguage，.h中添加属性方法

#import 

@interface ChangeLanguage : NSObject
#define FGGetStringWithKeyFromTable(key, tbl) [[ChangeLanguage sharedInstance] getStringForKey:key withTable:tbl]
@property(nonatomic, strong)NSString *language;

+(id)sharedInstance;

/**
 *  返回table中指定的key的值
 *
 *  @param key   key
 *  @param table table
 *
 *  @return 返回table中指定的key的值
 */
-(NSString *)getStringForKey:(NSString *)key withTable:(NSString *)table;

/**
 *  改变当前语言
 */
-(void)changeNowLanguage;

/**
 *  设置新的语言
 *
 *  @param language 新语言
 */
-(void)setNewLanguage:(NSString*)language;
@end

6.在.m中实现方法

#import "ChangeLanguage.h"
#import "AppDelegate.h"

#define CNS @"zh-Hans"
#define EN @"en"
#define LANGUAGE_SET @"langeuageset"

@interface ChangeLanguage()
@property(nonatomic,strong)NSBundle *bundle;
@end

@implementation ChangeLanguage
static ChangeLanguage *sharedModel;

+(id)sharedInstance
{
    if (!sharedModel)
    {
        sharedModel = [[ChangeLanguage alloc]init];
    }
    
    return sharedModel;
}

-(instancetype)init
{
    self = [super init];
    if (self)
    {
        [self initLanguage];
    }
    
    return self;
}

-(void)initLanguage
{
    NSString *tmp = [[NSUserDefaults standardUserDefaults]objectForKey:LANGUAGE_SET];
    NSString *path;
    //默认是中文
    if ([tmp isEqualToString:CNS] || !tmp)
    {
        tmp = CNS;
    }
    else
    {
        tmp = EN;
    }
    
    self.language = tmp;//更改之前语言
    path = [[NSBundle mainBundle]pathForResource:self.language ofType:@"lproj"];
    self.bundle = [NSBundle bundleWithPath:path];
}

- (NSString *)getStringForKey:(NSString *)key withTable:(NSString *)table
{
    if (self.bundle)
    {
        return NSLocalizedStringFromTableInBundle(key, table, self.bundle, @"");
    }
    
    return NSLocalizedStringFromTable(key, table, @"");
}

- (void)changeNowLanguage
{
    if ([self.language isEqualToString:EN])
    {
        [self setNewLanguage:CNS];
    }
    else
    {
        [self setNewLanguage:EN];
    }
}

-(void)setNewLanguage:(NSString *)language
{
    if ([language isEqualToString:self.language])
    {
        return;
    }
    
    //找到需要改成的语言路径
    if ([language isEqualToString:EN] || [language isEqualToString:CNS])
    {
        NSString *path = [[NSBundle mainBundle] pathForResource:language ofType:@"lproj"];
        self.bundle = [NSBundle bundleWithPath:path];
    }
    
    self.language = language;
    NSLog(@"%@", language);
    [[NSUserDefaults standardUserDefaults]setObject:language forKey:LANGUAGE_SET];
    [[NSUserDefaults standardUserDefaults]synchronize];
    [self resetRootViewController];
}

//重新设置
-(void)resetRootViewController
{
    AppDelegate *appDelegate =
    (AppDelegate *)[[UIApplication sharedApplication] delegate];
    UIStoryboard *SB = [UIStoryboard storyboardWithName:@"Main" bundle:nil];
    UITabBarController *tabBarController = [SB instantiateViewControllerWithIdentifier:@"tabBarController"];
    tabBarController = (UITabBarController*)appDelegate.window.rootViewController;
}

@end

7.具体使用：在具体方法中先调用changeNowLanguage方法，然后用FGGetStringWithKeyFromTable赋值即可；