iOS 在App内手动修改App语言

前期准备工作 https://www.jianshu.com/p/e7a3b9d610a2
主要包括添加需要本地化的语言，添加配置文件等步骤。

在Supporting Files文件夹下，New File -> Strings File。
创建的.strings文件命名为Language ,不可以命名为Localizable。

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在需要手动修改语言的文件中添加以下代码：

//添加一个显示切换项目语言的按钮

- (void)btnClick
{
    UIAlertController *alert =[UIAlertController alertControllerWithTitle:Localized(@"change") message:nil preferredStyle:UIAlertControllerStyleAlert];
    UIAlertAction *left = [UIAlertAction actionWithTitle:Localized(@"cancel") style:UIAlertActionStyleCancel handler:nil];
    UIAlertAction *simpleC = [UIAlertAction actionWithTitle:Localized(@"chinese") style:UIAlertActionStyleDefault handler:^(UIAlertAction * _Nonnull action) {
        
        [self chineseClick];
        
    }];
    UIAlertAction *comC = [UIAlertAction actionWithTitle:Localized(@"chineseC") style:UIAlertActionStyleDefault handler:^(UIAlertAction * _Nonnull action) {
        
        [self chineseCClick];
        
    }];
    UIAlertAction *english = [UIAlertAction actionWithTitle:Localized(@"english") style:UIAlertActionStyleDefault handler:^(UIAlertAction * _Nonnull action) {
        
        [self englishClick];
        
    }];
    [alert addAction:left];
    [alert addAction:simpleC];
    [alert addAction:comC];
    [alert addAction:english];
    [self presentViewController:alert animated:YES completion:nil];
}
- (void)chineseClick
{
    [[NSUserDefaults standardUserDefaults] setObject:@"zh-Hans" forKey:@"appLanguage"];

    [[NSUserDefaults standardUserDefaults] synchronize];
    [[NSNotificationCenter defaultCenter] postNotificationName:LanguageChanged object:nil];
    
}
- (void)chineseCClick
{
    
    [[NSUserDefaults standardUserDefaults] setObject:@"zh-Hant" forKey:@"appLanguage"];
    
    [[NSUserDefaults standardUserDefaults] synchronize];
    [[NSNotificationCenter defaultCenter] postNotificationName:LanguageChanged object:nil];
    
}
- (void)englishClick
{
    
    [[NSUserDefaults standardUserDefaults] setObject:@"en" forKey:@"appLanguage"];
    
    [[NSUserDefaults standardUserDefaults] synchronize];
    [[NSNotificationCenter defaultCenter] postNotificationName:LanguageChanged object:nil];
    
}

//添加语言发生变化的通知

- (void)viewWillAppear:(BOOL)animated
{
    [super viewWillAppear:animated];

    //添加通知中心，监听语言改变
    [[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(languageChanged) name:LanguageChanged object:nil];
    
}
- (void)viewWillDisappear:(BOOL)animated
{
    [super viewWillDisappear:animated];
    //移除通知中心
    [[NSNotificationCenter defaultCenter] removeObserver:self name:LanguageChanged object:nil];
}
//重新加载根视图控制器
- (void)languageChanged
{
    AppDelegate *appDelegate = (AppDelegate *)[UIApplication sharedApplication].delegate;
    [appDelegate mainVC];
}

//appDelegate.m

- (void)mainVC
{
    UINavigationController  *nav = [[UINavigationController alloc]initWithRootViewController:[MasterViewController new]];
    self.window.rootViewController = nav;
}

可以定义一个宏，方便本地化相应的字符串。

//获取当前保存在NSUserDefaults的本地语言

#define currentLanguage  [NSString stringWithFormat:@"%@",[[NSUserDefaults standardUserDefaults] objectForKey:@"appLanguage"]]

//根据获取语言文件所在路径
//文件名类型Type为lproj,即.lproj的文件夹.  zh-Hans.lproj和en.loproj
//存在NSUserDefaults的适合，中英文就分别设置zh-Hans和en，不可改变。

#define LanguagePath [[NSBundle mainBundle] pathForResource:currentLanguage ofType:@"lproj"]

//根据键值获取返回转换结果
//Language为语言文件名Language.string

#define Localized(key) [[NSBundle bundleWithPath:LanguagePath] localizedStringForKey:(key) value:nil table:@"Language"]


Localized(@"SpecialUserActionDanmu")

效果如下：