提供的解决方案实际上会返回设备的当前区域——而不是当前选择的语言。这些通常是同一件事。但是，如果我在北美，我将我的语言设置为日语，我的区域仍然是英语(美国)。为了检索当前选择的语言，你可以这样做:

NSString * language = [[NSLocale preferredLanguages] firstObject];

这将为当前选择的语言返回两个字母的代码。英语是“en”，西班牙语是“es”，德语是“de”，等等。更多例子，请参阅维基百科的条目(特别是639-1列):

ISO 639-1代码列表

然后，将这两个字母的代码转换为您想要显示的字符串就很简单了。如果是"en"，显示"English"。

EDIT

值得引用NSLocale.h中的头信息:

+ (NSArray *)preferredLanguages NS_AVAILABLE(10_5, 2_0); // note that this list does not indicate what language the app is actually running in; the [NSBundle mainBundle] object determines that at launch and knows that information

对应用语言感兴趣的人可以看看@mindvision的答案

-(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;

}

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+， 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

根据苹果文档

NSUserDefaults* defs = [NSUserDefaults standardUserDefaults];
NSArray* languages = [defs objectForKey:@"AppleLanguages"];
NSString* preferredLang = [languages objectAtIndex:0];

Swift 4的更新答案

let language = Bundle.main.preferredLocalizations.first