How to save the state of an UISwitch in SWIFT 4? [duplicate] - ios

Question

This question already has answers here:
How do i keep UISwitch state when changing ViewControllers?
(3 answers)
Closed 5 years ago.
I would like to save the State of an UISwitch after to change between View Controllers. Any help would be greatly appreciated!
I have a first View Controller with an UISwitch, to control the music in the background in different View Controllers:
#IBOutlet weak var SwitchMusic: UISwitch!
let defaults = UserDefaults.standard
var switchON : Bool = false
#IBAction func checkState(_ sender: UISwitch) {
if (sender.isOn == true)
{
switchON = true
defaults.set(switchON, forKey: "switchON")
MusicHelper.sharedHelper.playBackgroundMusic()
}
if (sender.isOn == false)
{
switchON = false
defaults.set(switchON, forKey: "switchON")
MusicHelper.sharedHelper.stopBackgroundMusic()
}
}
And a Second View Controller to load or no the music in the background if the switch is On or Off:
override func viewDidLoad() {
super.viewDidLoad()
if defaults.value(forKey: "switchON") != nil{
let switchON: Bool = defaults.value(forKey: "switchON") as! Bool
if switchON == true{
MusicHelper.sharedHelper.playBackgroundMusic()
}
else if switchON == false{
MusicHelper.sharedHelper.stopBackgroundMusic()
}
}
}
Also I have a class with the music:
class MusicHelper {
let defaults = UserDefaults.standard
static let sharedHelper = MusicHelper()
var musicBackgroundIntro:AVAudioPlayer = AVAudioPlayer()
func playBackgroundMusic() {
do {
let audioPath = Bundle.main.path(forResource: "Music", ofType: "mp3")
try musicBackgroundIntro = AVAudioPlayer(contentsOf: NSURL(fileURLWithPath: audioPath!) as URL)
musicBackgroundIntro.numberOfLoops = -1
musicBackgroundIntro.prepareToPlay()
musicBackgroundIntro.play()
} catch {
print("Cannot play the file")
}
}
func stopBackgroundMusic() {
musicBackgroundIntro.stop()
}
}
Now it is working perfectly the music in the background between View Controllers, and it is possible to turn off and on... but unfortunately do not save the current state of the UISwitch, and always when I enter in the First View Controller the state of the Switch is On.
Also any idea that how will be possible to apply in a Slider too?
Any help would be greatly appreciated!
Thanks

Answer 1

The easiest way for you would be to create a static var isSwitchOn: Bool = false
This state will be preserved between back and forth transitions.

Answer 2

You should reflect the state, if music is playing...
class MusicHelper {
public isPlaying: Bool {
get {
return musicBackgroundIntro.isPlaying
}
}
// your stuff here..
}
That way in other view controllers:
SwitchMusic.isOn = MusicHelper.sharedHelper.isPlaying
If you need other view controllers to update in response to this, you can add a delegate event (aka observer) if necessary.

Answer 3

Try something like that: Use the UISwitch as an #IBOutlet.
#IBOutlet weak var checkState: UISwitch!
override func viewDidLoad() {
super.viewDidLoad()
self.checkState.addTarget(self, action: #selector(action(sender:)), for: .valueChanged)
}
// Save state
func action(sender: UISwitch) {
let userDefaults = UserDefaults.standard
userDefaults.set(sender.isOn, forKey:"identifier")
}
// Retrieve state
override func viewWillAppear(_ animated: Bool) {
super.viewWillAppear(animated)
let userDefaults = UserDefaults.standard.bool(forKey: "identifier")
self.checkState.setOn(userDefaults, animated: false)
}

Answer 4

You can give the switch a default value when it's created in viewcontroller1.
Assign the (default.value(forKey:"switchOn") as! Bool ) ?? false to that switch.