//监听显示模式的变化
   DistributedNotificationCenter.default().addObserver(self,
                                                            selector: #selector(appleInterfaceThemeChanged(_:)),
                                                            name: NSNotification.Name(rawValue: "AppleInterfaceThemeChangedNotification"),
                                                            object: nil)


 func appleInterfaceThemeChanged(_ notice:Notification){
      //......  
 }

extension NSObject{
    func isDarkModel() -> Bool{
        if let dic = user.persistentDomain(forName: UserDefaults.globalDomain),let style = dic["AppleInterfaceStyle"] as? String {
            if style.compare("Dark").rawValue == 0{
                return true
            }
        }
        return false
    }
}