SwiftUI: Run Code on the view when the CLAuthorizationStatus changes - swiftui

Question

I want to run some code (fetching records to populate a List) when permission is granted for location access.
Here is my Location Manager:
import Foundation
import CoreLocation
import Combine
class LocationManager: NSObject, ObservableObject, CLLocationManagerDelegate {
private let locationManager = CLLocationManager()
#Published var locationStatus: CLAuthorizationStatus?
override init() {
super.init()
locationManager.delegate = self
locationManager.requestWhenInUseAuthorization()
}
func locationManager(_ manager: CLLocationManager, didChangeAuthorization status: CLAuthorizationStatus) {
locationStatus = status
print("This is the Model")
print(status == .authorizedWhenInUse)
}
}
And here is my view:
import SwiftUI
import CoreLocation
struct HorizontalPerformanceListView: View {
#ObservedObject var locationManager: LocationManager = LocationManager()
var performanceSet: PerformanceSet
var body: some View {
VStack (spacing: 10) {
//iterate over a fetched records
}
.onReceive(locationManager.$locationStatus) { _ in self.runCode() }
}
func runCode(){
print("This is the View")
print(locationManager.locationStatus == .authorizedWhenInUse)
if(locationManager.locationStatus == .authorizedWhenInUse){
print("run code here")
}
}
}
When the user prompted for location permission and specifies "allow while using app", I'd expect the "RunCode" func to run and for locationManager.locationStatus to be set to .authorizedWhenInUse.
The console prints instead:
This is the View
false
This is the Model
true
This is the View
false
This is the Model
true
The locationStatus is clearly changing in the model when permission is granted but my view still thinks access isn't there.
Clearly I am doing something wrong (I am somewhat new to SwiftUI/Combine) - I'd appreciate any help.

Answer 1

Change #ObservedObject to #StateObject. #StateObject is for data your view owns (i.e. instantiates), #ObservedObject is for data not owned by your view (i.e. passed in as an argument to your view).
Additionally, the publisher is an objectWillChange notification (i.e. it hasn't changed yet). Try using an asyncAfter delay to observe it correctly.
import SwiftUI
import CoreLocation
struct HorizontalPerformanceListView: View {
#StateObject var locationManager: LocationManager = LocationManager()
var performanceSet: PerformanceSet
var body: some View {
VStack (spacing: 10) {
//iterate over a fetched records
}
.onReceive(locationManager.$locationStatus) { _ in self.runCode() }
}
func runCode(){
DispatchQueue.main.asyncAfter(deadline: .now() + 1) {
print("This is the View")
print(locationManager.locationStatus == .authorizedWhenInUse)
if(locationManager.locationStatus == .authorizedWhenInUse){
print("run code here")
}
}
}
}