Save map annotation using UserDefaults - swift

Question

I have been searching relentlessly for this solution and left with no choice except to rely on the expertise here on Stackoverflow. I am working on saving a map annotation if the app closes and I have been using the UserDefault to save the annotation.
This is the Objective C code that I found and I tried converting it into Swift and I think there is an error with it. I am not too sure. I place this code at viewDidLoad()
This is the save annotation
var pinnedAnnotation: CLLocationCoordinate2D = (parkedCarAnnotation?.coordinate)!
var coordinateData: NSData = NSData(bytesNoCopy: pinnedAnnotation, length: sizeof(pinnedAnnotation), freeWhenDone: false)
UserDefaults.standard.set(coordinateData, forKey: pinnedAnnotation)
UserDefaults.standard.synchronize()
And I needed a load annotation when the app open.
I dont know if viewDidLoad is the right place to put. Previously I put it in a mapView function of updatingLocation
Edited: Added code for further clarification of what I have done that needed to be corrected
override func viewDidLoad() {
super.viewDidLoad()
mapView.delegate = self as MKMapViewDelegate
checkLocationAuthorizationStatus()
tabBar.delegate = self
if UserDefaults.standard.object(forKey: "pinnedAnnotation") != nil {
let annotation = MKPointAnnotation()
self.mapView.addAnnotation(annotation)
}
}
func locationManager(_ manager: CLLocationManager, didUpdateLocations locations: [CLLocation]) {
let pinnedAnnotation: CLLocationCoordinate2D = (parkedCarAnnotation?.coordinate)!
let locationData = ["latitude": parkedCarAnnotation?.coordinate.latitude, "longitude": parkedCarAnnotation?.coordinate.longitude]
UserDefaults.standard.set(locationData, forKey: "pinnedAnnotation")
UserDefaults.standard.synchronize()
print("Saving data ", UserDefaults.standard.set(locationData, forKey: "pinnedAnnotation"))
}
func tabBar(_ tabBar: UITabBar, didSelect item: UITabBarItem) {
if(item.tag == 0){
if mapView.annotations.count == 1{
mapView.addAnnotation(parkedCarAnnotation!)
} else {
mapView.removeAnnotation(mapView.annotations as! MKAnnotation)
}
}
extension ViewController: MKMapViewDelegate {
func mapView(_ mapView: MKMapView, viewFor annotation: MKAnnotation) -> MKAnnotationView? {
if let annotation = annotation as? ParkingSpot{
let identifier = "pin"
var view: MKPinAnnotationView
view = MKPinAnnotationView(annotation: annotation, reuseIdentifier: identifier)
view.canShowCallout = true
view.animatesDrop = true
view.pinTintColor = UIColor.orange
view.calloutOffset = CGPoint(x: -8, y: -3)
view.rightCalloutAccessoryView = UIButton.init(type:.detailDisclosure) as UIView
return view
} else {
return nil
}
}
extension ViewController: CLLocationManagerDelegate{
func mapView(_ mapView: MKMapView, didUpdate userLocation: MKUserLocation) {
centerMapOnLocation(location: CLLocation(latitude: userLocation.coordinate.latitude, longitude: userLocation.coordinate.longitude))
let locationServiceCoordinate = LocationService.instance.locationManager.location!.coordinate
parkedCarAnnotation = ParkingSpot(title: "My Parking Spot", locationName: "Find your way back to your car location", coordinate: CLLocationCoordinate2D(latitude: locationServiceCoordinate.latitude, longitude: locationServiceCoordinate.longitude))
}
}

Answer 1

I'm not entirely sure what you're asking...
For starters when you're saving data to UserDefaults the key needs to be a string, I also believe you'll need to save you data in UserDefaults as a Dictionary
let locationData = ["lat": parkedCarAnnotation?.coordinate?.latitude, "long": parkedCarAnnotation?.coordinate.longitude]
UserDefaults.standard.set(locationData, forKey: "pinned_annotation")
And then to retrieve the data you would call
if let annotationData = UserDefaults.standard.object(forKey: "pinned_annotation") as? Dictionary {
guard let lat = annotationData["lat"], let long = annotationData["long"] else { return }
let coordinate = CLLocationCoordinate2D(latitude: lat, longitude: long)
}
Now you should hopefully be able to set your annotation with the coordinate