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

I actually misread the original question, thought it asked for the "app UI" language (that's what I had googled for), not the "device UI", in which case the best answers would be the ones using preferredLocalizations, but those answers still give you a code, there is one more step to get a nice string to display. So, while the "device UI" language is already answered, if you want to display a nice string for which of the UI languages you support is currently in use, obviously the simplest solution is:

NSLocalizedString(@"currentLanguage", @"")

在你的每一个UI本地化中你都指定了你想要的显示方式。例如，在你的。strings文件的en版本中，你会有:

"currentLanguage"="English";

在你的fr版本的.strings文件中，你会有:

"currentLanguage"="Francais";

等。不要混淆代码等，你可以让你自己的字符串很好地匹配你的UI。

两封信的格式。苹果使用ISO标准ISO-3166。

NSString *localeCountryCode = [[NSLocale autoupdatingCurrentLocale] objectForKey:NSLocaleCountryCode];

你可以使用NSLocale的displayNameForKey:value:方法:

// get a French locale instance
NSLocale *frLocale = [[[NSLocale alloc] initWithLocaleIdentifier:@"fr_FR"] autorelease];

// use it to get translated display names of fr_FR and en_US
NSLog(@"%@", [frLocale displayNameForKey:NSLocaleIdentifier value:@"fr_FR"]);
NSLog(@"%@", [frLocale displayNameForKey:NSLocaleIdentifier value:@"en_US"]);

这将打印出:

français (France)
anglais (États-Unis)

如果你为initWithLocaleIdentifier:和displayNameForKey:value:方法指定了相同的语言环境标识符，那么它会给你语言的本机名称。我发现，如果你删除国家代码，只使用fr和en，它也会从显示名称中省略国家(至少在Mac OS X上，不确定iOS)。

斯威夫特3

let locale = Locale.current
let code = (locale as NSLocale).object(forKey: NSLocale.Key.countryCode) as! String?
print(code!)

从iOS 9开始，如果你只想要语言代码而不需要国家代码，你将需要这种帮助函数——因为语言将包含国家代码。

// gets the language code without country code in uppercase format, i.e. EN or DE
NSString* GetLanguageCode()
{
    static dispatch_once_t onceToken;
    static NSString* lang;
    dispatch_once(&onceToken, ^
    {
        lang = [[[NSLocale preferredLanguages] objectAtIndex:0] uppercaseString];
        NSRegularExpression* regex = [NSRegularExpression regularExpressionWithPattern:@"^[A-Za-z]+" options:0 error:nil];
        NSTextCheckingResult* match = [regex firstMatchInString:lang options:0 range:NSMakeRange(0, lang.length)];
        if (match.range.location != NSNotFound)
        {
            lang = [lang substringToIndex:match.range.length];
        }
    });
    return lang;
}