@property (class, readonly, copy) NSArray<NSString *> *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
这个数组是根据设置中的首选语言顺序给出的数组.
可以注意到,注释中解释app真正running in 的语言需要在 NSBundle.mainBundle中寻找.查看NSBundle.h可以找到以下代码
/* Methods for dealing with localizations. */
@property (readonly, copy) NSArray<NSString *> *preferredLocalizations;
// 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
