How to read settings bundle when I go back to App?

Question

I created "updateheading" in settings bundle

If user leave the app, go to setting to change value, when user go back the app, locationManager should start/stop base on the updated value.

But the app does not run viewWillAppear. How to read updated value?

private let locationManager : CLLocationManager = CLLocationManager()

override func viewDidLoad() {
    super.viewDidLoad()

    locationManager.requestWhenInUseAuthorization()
    locationManager.delegate = self
}
override func viewWillAppear(_ animated: Bool) {

    let userDefault = UserDefaults.standard
    let updateheading = userDefault.object(forKey: "updateheading") as! Bool
    if(updateheading){
        locationManager.startUpdatingHeading()
    }else{
        locationManager.stopUpdatingHeading()
    }
}

Let me get that clear, you have a settings bundle, right? If so, how are you reading from that bundle? — Ashraf Tawfeeq, Jan 08 '18 at 10:48
yes, I have a settings bundle `Root.plist`, and I use this to read the value in bundle `let updateheading = userDefault.object(forKey: "updateheading") as! Bool` — CL So, Jan 08 '18 at 11:06
I think your answer might be here https://stackoverflow.com/questions/6291477/how-to-retrieve-values-from-settings-bundle-in-objective-c — Ashraf Tawfeeq, Jan 08 '18 at 13:10

score 2 · Accepted Answer · answered Jan 08 '18 at 11:25

View controller do not responding on application state. It is responsibility of AppDelegate. But you can subscribe for notifications.

var observer: Any?

override func viewWillAppear(_ animated: Bool) {
    super.viewDidAppear(animated)
    observer = NotificationCenter.default.addObserver(forName: NSNotification.Name.UIApplicationDidBecomeActive, object: nil, queue: .main) { (_) in
        doUpdate()
    }
    doUpdate()
}

override func viewWillDisappear(_ animated: Bool) {
    super.viewWillDisappear(animated)
    observber = nil
}

Where doUpdate is your current code.

PS: "If you override viewWillAppear, you must call super at some point in your implementation." (c) Apple Docs

How to read settings bundle when I go back to App?

1 Answers1