对于Swift 3:

NSLocale。preferredLanguages[0]作为字符串

如果你正在寻找首选语言代码(“en”，“de”，“es”…)，和本地化的首选语言名称(当前地区)，这里有一个简单的Swift扩展:

extension Locale {
    static var preferredLanguageIdentifier: String {
        let id = Locale.preferredLanguages.first!
        let comps = Locale.components(fromIdentifier: id)
        return comps.values.first!
    }

    static var preferredLanguageLocalizedString: String {
        let id = Locale.preferredLanguages.first!
        return Locale.current.localizedString(forLanguageCode: id)!
    }
}

根据苹果文档

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

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;
}

@amir在Swift中的回应:

// Get language prefered by user
let langageRegion = NSLocale.preferredLanguages().first!
let languageDic = NSLocale.componentsFromLocaleIdentifier(langageRegion)
let language = languageDic[NSLocaleLanguageCode]