Problem displaying user location on screen

Question

I am trying to display user location coordinates on screen but nothing shows up when i run the app even though i can see coordinates in console. And the second problem i have is when i press the stop button the location updates do not stop.

LocationManager:

import Foundation
import CoreLocation

class LocationManager: NSObject, ObservableObject, CLLocationManagerDelegate{
    let locationManager = CLLocationManager()
    @Published var location: CLLocationCoordinate2D?
    
    override init(){
        super.init()
        locationManager.delegate = self
    }
    
    func startTracking() {
        locationManager.requestAlwaysAuthorization()
        locationManager.desiredAccuracy = kCLLocationAccuracyBest
        locationManager.distanceFilter = kCLDistanceFilterNone
        locationManager.allowsBackgroundLocationUpdates = true
        locationManager.startUpdatingLocation()
    }
    
    func stopTracking() {
        print("stop test")
        locationManager.stopUpdatingLocation()
        locationManager.allowsBackgroundLocationUpdates = false
    }
    
    func locationManager(_ manager: CLLocationManager, didUpdateLocations locations: [CLLocation]) {
        let tempLocation = locations.last?.coordinate
        print(tempLocation)
        DispatchQueue.main.async {
            self.location = tempLocation
        }
    }
}

View:

import SwiftUI
struct ContentView: View {
    @StateObject var locationManager = LocationManager()
    
    var body: some View {
        VStack{
            startLocationTrackingButton()
            stopLocationTrackingButton()
            
            if let location = locationManager.location {
                Text("Your location: \(location.latitude), \(location.longitude)")
            }
            
        }
    }
}
struct startLocationTrackingButton: View{
    @StateObject var locationManager = LocationManager()
    
    var body: some View{
        Button("START"){
            locationManager.startTracking()
            
        }
    }
}
struct stopLocationTrackingButton: View{
    @StateObject var locationManager = LocationManager()
    
    var body: some View{
        Button("STOP"){
            locationManager.stopTracking()
        }
    }
}

Thanks for help!

Abizern · Accepted Answer · 2021-07-16 14:44:09Z

Each of your views has:

@StateObject var locationManager = LocationManager()

You are creating a different Location manager for each one. Try doing it as:

truct ContentView: View {
    @StateObject var locationManager = LocationManager()
    
    var body: some View {
        VStack{
            StartLocationTrackingButton(manager: locationManager)
            StopLocationTrackingButton(manager: locationManager)
            
            if let location = locationManager.location {
                Text("Your location: \(location.latitude), \(location.longitude)")
            }
            
        }
    }
}
struct StartLocationTrackingButton: View{
    @ObservedObject var manager: LocationManager
    
    var body: some View{
        Button("START"){
            manager.startTracking()
            
        }
    }
}
struct stopLocationTrackingButton: View{
    @ObservedObject var manager: LocationManager
    
    var body: some View{
        Button("STOP"){
            manager.stopTracking()
        }
    }
}

Only use @StateObject when you are creating and owning the object. If you are passing on ObservableObject to another view, then that View should declare it as @ObservedObject and don't give it an initial value.

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