也许你应该补充这个(在.pch文件#import后):

extern NSBundle* bundle; // Declared on Language.m

#ifdef NSLocalizedString
    #undef NSLocalizedString
    // Delete this line to avoid warning
    #warning "Undefining NSLocalizedString"
#endif

#define NSLocalizedString(key, comment) \
    [bundle localizedStringForKey:(key) value:@"" table:nil]

你觉得Swift 3的这个解决方案怎么样?

extension String {

    func localized(forLanguage language: String = Locale.preferredLanguages.first!.components(separatedBy: "-").first!) -> String {

        guard let path = Bundle.main.path(forResource: language == "en" ? "Base" : language, ofType: "lproj") else {

            let basePath = Bundle.main.path(forResource: "Base", ofType: "lproj")!

            return Bundle(path: basePath)!.localizedString(forKey: self, value: "", table: nil)
        }

        return Bundle(path: path)!.localizedString(forKey: self, value: "", table: nil)
    }
}

简单的用法:

"report".localized(forLanguage: "pl") //forced language
"report".localized() //default language selected by user in settings, in case when your app doesnt support selected lanaguage, the default one is selected, here is an english.

这里有一个不错的解决方案，它不需要重新启动应用程序。

https://github.com/cmaftuleac/BundleLocalization

这个实现通过在NSBundle内部进行调整来工作。这个想法是你在NSBundle对象的实例上重写localizedStringForKey方法，然后用不同的语言在不同的bundle上调用这个方法。简单而优雅的完全兼容所有类型的资源。

斯威夫特版本:

NSUserDefaults.standardUserDefaults().setObject(["fr"], forKey: "AppleLanguages")
NSUserDefaults.standardUserDefaults().synchronize()

也许你应该补充这个(在.pch文件#import后):

extern NSBundle* bundle; // Declared on Language.m

#ifdef NSLocalizedString
    #undef NSLocalizedString
    // Delete this line to avoid warning
    #warning "Undefining NSLocalizedString"
#endif

#define NSLocalizedString(key, comment) \
    [bundle localizedStringForKey:(key) value:@"" table:nil]

如前所述，只要做:

[[NSUserDefaults standardUserDefaults] setObject: [NSArray arrayWithObjects:@"el", nil] forKey:@"AppleLanguages"];

但是为了避免不得不重新启动应用程序，请将该行放在main的main方法中。m，就在UIApplicationMain(…)之前。