在Swift 4.2和Xcode 10.1中

let language = NSLocale.preferredLanguages[0]
debugPrint(language)//en

在Swift 5.x中

let langStr = Locale.current.languageCode
debugPrint(langStr ?? "") //en  el

-(NSString *)returnPreferredLanguage { //as written text

NSUserDefaults * defaults = [NSUserDefaults standardUserDefaults];
NSArray *preferredLanguages = [defaults objectForKey:@"AppleLanguages"];
NSString *preferredLanguageCode = [preferredLanguages objectAtIndex:0]; //preferred device language code
NSLocale *enLocale = [[NSLocale alloc] initWithLocaleIdentifier:@"en"]; //language name will be in English (or whatever)
NSString *languageName = [enLocale displayNameForKey:NSLocaleIdentifier value:preferredLanguageCode]; //name of language, eg. "French"
return languageName;

}

在Swift 4.2和Xcode 10.1中

let language = NSLocale.preferredLanguages[0]
debugPrint(language)//en

在Swift 5.x中

let langStr = Locale.current.languageCode
debugPrint(langStr ?? "") //en  el

快5.倍 我们可以使用设备语言 但是它会返回en表示英文，zh表示简体中文，zh表示繁体中文

事实上，如果我们能得到这样的东西会更有帮助。 zh-Hans表示简体中文 zh-Hant代表中文-繁体

这里zh是语言代码，Hans是scriptCode。

解决方案:

本地扩展( 统计var首选语言代码:[字符串] 地方preferredLanguages compactMap。( 如果脚本代码=本地(标识符:$0)。 let languageCode =本地(标识符:$0)。languageCode ( 返回语言+ - +脚本代码 ) 返回本地(id: $0) ) ) ) For example:[“zh-Hant”、“”、“zh-Hans”、“ko”、“ja”、“es”、“德”、“n”、“”、“it”)

iOS13, Swift 5+， WWDC2019 https://developer.apple.com/videos/play/wwdc2019/403/

用户可以独立于操作系统语言选择应用程序的首选语言。

你可以使用这些:

    // Returns a list of the user's preferred languages.
    // Maybe more than (or none of) your app supports!
    Locale.preferredLanguages

    // a subset of this bundle's localizations, re-ordered into the preferred order
    // for this process's current execution environment; the main bundle's preferred localizations
    // indicate the language (of text) the user is most likely seeing in the UI
    Bundle.main.preferredLocalizations



    // The current running app language
    Bundle.main.preferredLocalizations.first

    // list of language names this bundle appears to be localized to
    Bundle.main.localizations

SWIFT-4

 // To get device default selected language. It will print like short name of zone. For english, en or spain, es.

let language = Bundle.main.preferredLocalizations.first! as NSString
print("device language",language)