How do i keep UISwitch state when changing ViewControllers?

Question

When I move from one view controller to another, the switch on the first controller resets itself and does not retain its state. How can I make it save its state when come

Answer 1

just after code connect UISwitch to IBoutlet.

class ViewController: UIViewController {

    @IBOutlet weak var switchButton: UISwitch!

    @objc func switchStateDidChange(_ sender:UISwitch!)
    {
        if (sender?.isOn == true){
            print("on")
        }
        else {
            print("off")
        }
        UserDefaults.standard.set(sender.isOn, forKey: "switchState")
        UserDefaults.standard.synchronize()
    }

   override func viewWillAppear(_ animated: Bool) {
        super.viewWillAppear(false)
        switchButton?.isOn =  UserDefaults.standard.bool(forKey: "switchState")
        switchButton?.addTarget(self, action: #selector(switchStateDidChange(_:)), for: .touchUpInside)
    }
}

Answer 2

Since you're syncing the on/off state of the switch you could on viewWillAppear: or viewDidAppear: set the state of the switch to the value stored in NSUserDefaults

Something along the lines of

override func viewWillAppear(animated: Bool) {
  self.switchButton.on = NSUserDefaults.standardUserDefaults().boolForKey(switchKey)
}

Answer 3

Xcode 8.3 • Swift 3.1

import UIKit

class 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")
    }
}