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

对于获得用户设备当前语言使用以下它的代码，它为我工作。

NSString * myString = [[NSLocale preferredlanguage]objectAtIndex:0];

iOS13, Swift 5+

Locale.preferredLanguages.first

iOS 9的解决方案:

NSString *language = [[NSLocale preferredLanguages] objectAtIndex:0];

language = "en-US"

NSDictionary *languageDic = [NSLocale componentsFromLocaleIdentifier:language];

languageDic将拥有所需的组件

NSString *countryCode = [languageDic objectForKey:@"kCFLocaleCountryCodeKey"];

countryCode = "US"

NSString *languageCode = [languageDic objectForKey:@"kCFLocaleLanguageCodeKey"];

密码:

我用这个

    NSArray *arr = [NSLocale preferredLanguages];
for (NSString *lan in arr) {
    NSLog(@"%@: %@ %@",lan, [NSLocale canonicalLanguageIdentifierFromString:lan], [[[NSLocale alloc] initWithLocaleIdentifier:lan] displayNameForKey:NSLocaleIdentifier value:lan]);
}

忽略内存泄漏..

结果是

2013-03-02 20:01:57.457 xx[12334:907] zh-Hans: zh-Hans 中文（简体中文）
2013-03-02 20:01:57.460 xx[12334:907] en: en English
2013-03-02 20:01:57.462 xx[12334:907] ja: ja 日本語
2013-03-02 20:01:57.465 xx[12334:907] fr: fr français
2013-03-02 20:01:57.468 xx[12334:907] de: de Deutsch
2013-03-02 20:01:57.472 xx[12334:907] nl: nl Nederlands
2013-03-02 20:01:57.477 xx[12334:907] it: it italiano
2013-03-02 20:01:57.481 xx[12334:907] es: es español

将语言代码(如en_US)翻译成英语(United States)是NSLocale的内置特性，NSLocale并不关心你从哪里获得语言代码。因此，确实没有理由像公认的答案所建议的那样实现自己的翻译。

// Example code - try changing the language codes and see what happens
NSLocale *locale = [[NSLocale alloc] initWithLocaleIdentifier:@"en"];
NSString *l1 = [locale displayNameForKey:NSLocaleIdentifier value:@"en"];
NSString *l2 = [locale displayNameForKey:NSLocaleIdentifier value:@"de"];
NSString *l3 = [locale displayNameForKey:NSLocaleIdentifier value:@"sv"];
NSLog(@"%@, %@, %@", l1, l2, l3);

印刷:英语，德语，瑞典语

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