更改ViewController时如何保持UISwitch状态？

Xpre 8.3•Swift 3.1

import UIKitclass ViewController: UIViewController {    @IBOutlet weak var switchButton: UISwitch!    override func viewDidLoad() {        super.viewDidLoad()        switchButton.isOn =  UserDefaults.standard.bool(forKey: "switchState")    }    @IBAction func saveSwitchPressed(_ sender: UISwitch) {        UserDefaults.standard.set(sender.isOn, forKey: "switchState")    }}