`+ (NSString *)mj_localizedStringForKey:(NSString *)key value:(NSString *)value` 方法中`NSString *i18nFolderPath = [bundle pathForResource:language ofType:@"lproj"];`获取到的i18nFolderPath为nil,导致`mj_defaultI18nBundle = [NSBundle bundleWithPath:i18nFolderPath];`执行有异常提示: **NSBundle (null) initWithPath failed because the resolved path is empty or nil**