In the following code, I have a LocationManager
class which provides the city name of the current location via the @Published
property wrapper lastSearchedCity
.
Then I have a SearchManagerViewModel
class that should be in charge of presenting the city name on SwiftUI
views based on some conditions (not currently shown in the code below) via the @Published
property wrapper cityName
. It properly shows the city name when I call the searchAndSetCity()
method from ContentView.swift
inside an onAppear
modifier.
My issue is that if the user turned Location Services
off and turns it back On while he/she is in the ContentView.swift
the Text
view doesn't update, which is understandable since the searchAndSetCity()
method would need to be called again.
How can I call the searchAndSetCity()
method located inside the SearchManagerViewModel
class every time the locationManagerDidChangeAuthorization(_ manager: CLLocationManager)
method is called? I believed this method is called every time the authorization status changes.
LocationManager Class
final class LocationManager: NSObject, ObservableObject, CLLocationManagerDelegate {
private let locationManager = CLLocationManager()
@Published var lastSearchedCity = ""
var hasFoundOnePlacemark:Bool = false
func checkIfLocationServicesIsEnabled(){
DispatchQueue.global().async {
if CLLocationManager.locationServicesEnabled(){
self.locationManager.delegate = self
self.locationManager.desiredAccuracy = kCLLocationAccuracyBest/// kCLLocationAccuracyBest is the default
self.checkLocationAuthorization()
}else{
// show message: Services desabled!
}
}
}
private func checkLocationAuthorization(){
switch locationManager.authorizationStatus{
case .notDetermined:
locationManager.requestWhenInUseAuthorization()
case .restricted:
// show message
case .denied:
// show message
case .authorizedWhenInUse, .authorizedAlways:
/// app is authorized
locationManager.startUpdatingLocation()
default:
break
}
}
func locationManagerDidChangeAuthorization(_ manager: CLLocationManager) {
checkLocationAuthorization()
}
func locationManager(_ manager: CLLocationManager, didUpdateLocations locations: [CLLocation]) {
hasFoundOnePlacemark = false
CLGeocoder().reverseGeocodeLocation(manager.location!, completionHandler: {(placemarks, error)-> Void in
if error != nil {
self.locationManager.stopUpdatingLocation()
// show error message
}
if placemarks!.count > 0 {
if !self.hasFoundOnePlacemark{
self.hasFoundOnePlacemark = true
let placemark = placemarks![0]
self.lastSearchedCity = placemark.locality ?? ""
}
self.locationManager.stopUpdatingLocation()
}else{
// no places found
}
})
}
}
SearchManagerViewModel Class
class SearchManagerViewModel: ObservableObject{
@Published var cityName = "" // use this directly in SwifUI views
@ObservedObject private var locationManager = LocationManager()
// Call this directly fron onAppear in SwiftUI views
// This method is more complex than what is shown here. It handles other things like HTTP requests etc.
func searchAndSetCity(){
locationManager.checkIfLocationServicesIsEnabled()
self.cityName = locationManager.lastSearchedCity
}
}
ContentView.swift
struct ContentView: View {
@StateObject private var searchManager = SearchManagerViewModel()
var body: some View {
VStack {
Text(searchManager.cityName)
.font(.callout)
}
.onAppear{
searchManager.searchAndSetCity()
}
}
}