Cannot get #EnvironmentObject in Controller - ios

Question

I'm trying to use #EnvironmentObject to control some aspects of my app. The issue I'm having is that one of my controllers can't access the environment object. I get the fatal error "No #ObservableObject of type Environment found".
I've searched other questions, and every solution I could find consisted of sending .environmentObject(myEnvironment) to the view in question. The problem is this is not a view, and I don't seem to have that option.
Also, in my SceneDelegate I send the environmentObject to the first view, so that is not the problem.
Here is my code.
First, I created a model to declare all my environment variables
Environment
struct Environment {
var showMenu: Bool
var searchText: String
var location : Location
init() {
self.showMenu = false
self.searchText = ""
self.location = Location()
}
}
Next I have a controller which purpose is to handle any actions related to the environment, right now it has none
EnvironmentController
import Foundation
class EnvironmentController : ObservableObject {
#Published var environment = Environment()
}
Now, in the SceneDelegate I call the NextDeparturesView, which in turn calls, the MapView.
MapView
import SwiftUI
import MapKit
//MARK: Map View
struct MapView : UIViewRepresentable {
#EnvironmentObject var environmentController: EnvironmentController
var locationController = LocationController()
func makeUIView(context: Context) -> MKMapView {
MKMapView(frame: .zero)
}
func updateUIView(_ uiView: MKMapView, context: Context) {
let coordinate = CLLocationCoordinate2D(
latitude: environmentController.environment.location.latitude,
longitude: environmentController.environment.location.longitude)
let span = MKCoordinateSpan(latitudeDelta: 0.1, longitudeDelta: 0.1)
let region = MKCoordinateRegion(center: coordinate, span: span)
uiView.showsUserLocation = true
uiView.setRegion(region, animated: true)
}
}
You'll notice that in the MapView I call the LocationController, which is where the fatal error occurs
LocationController
import SwiftUI
import MapKit
import CoreLocation
final class LocationController: NSObject, CLLocationManagerDelegate, ObservableObject {
//MARK: Vars
#EnvironmentObject var environmentController: EnvironmentController
#ObservedObject var userSettingsController = UserSettingsController()
//var declaration - Irrelevant code to the question
//MARK: Location Manager
var locationManager = CLLocationManager()
//MARK: Init
override init() {
//more irrelevant code
super.init()
//Ask for location access
self.updateLocation()
}
//MARK: Functions
func updateLocation() {
locationManager.delegate = self
locationManager.desiredAccuracy = kCLLocationAccuracyBest
if locationManager.responds(to: #selector(CLLocationManager.requestAlwaysAuthorization)){
locationManager.requestAlwaysAuthorization()
}
else {
locationManager.startUpdatingLocation()
}
}
//MARK: CLLocationManagerDelegate methods
func locationManager(_ manager: CLLocationManager, didFailWithError error: Error) {
print("Error updating location :%#", error)
}
func locationManager(_ manager: CLLocationManager, didChangeAuthorization status: CLAuthorizationStatus) {
switch status {
case .notDetermined:
self.setDefaultLocation()
break
case .restricted:
self.setDefaultLocation()
break
case .denied:
self.setDefaultLocation()
break
default:
locationManager.startUpdatingLocation()
}
}
func locationManager(_ manager: CLLocationManager, didUpdateLocations locations: [CLLocation]) {
let currentLocation = manager.location?.coordinate
self.environmentController.environment.location.latitude = Double(currentLocation!.latitude)
self.environmentController.environment.location.longitude = Double(currentLocation!.longitude)
manager.stopUpdatingLocation()
}
//MARK: Other Functions
func recenter() {
locationManager.startUpdatingLocation()
}
func setDefaultLocation() {
if self.$userSettingsController.userCity.wrappedValue == "" {
self.environmentController.environment.location.latitude = 0.0
self.environmentController.environment.location.longitude = 0.0
} else {
self.environmentController.environment.location.latitude = self.citiesDictionary[self.userSettingsController.userCity]!.latitude
self.environmentController.environment.location.longitude = self.citiesDictionary[self.userSettingsController.userCity]!.longitude
}
}
}
So, this is where the fatal error occurs. For instance, my app usually calls setDefaultLocation() first, and the app is crashing there. Any idea what I am doing wrong, or how to solve it?
Thank you in advance.
EDIT
After much help from #pawello2222 I've solved my problem, however with some changes to the overall structure of my application.
I will accept his answer as the correct one, but I'll provide a list of things that I did, so anyone seeing this in the future might get nudged in the right direction.
I was wrongly assuming that View and UIViewRepresentable could both access the #EnvironmentObject. Only View can.
In my Environment struct, instead of a Location var, I now have a LocationController, so the same instance is used throughout the application. In my LocationController I now have a #Published var location: Location, so every View has access to the same location.
In structs of the type View I create the #EnvironmentObject var environmentController: EnvironmentController and use the LocationController associated with it. In other class types, I simply have an init method which receives a LocationController, which is sent through the environmentController, for instance, when I call MapView I do: MapView(locController: environmentController.environment.locationController) thus insuring that it is the same controller used throughout the application and the same Location that is being changed. It is important that to use #ObservedObject var locationController: LocationController in classes such as MapView, otherwise changes won't be detected.
Hope this helps.

Answer 1

Don't use #EnvironmentObject in your Controller/ViewModel (in fact anywhere outside a View). If you want to observe changes to Environment in your Controller you can do this:
class Environment: ObservableObject {
#Published var showMenu: Bool = false
#Published var searchText: String = ""
#Published var location : Location = Location()
}
class Controller: ObservableObject {
#Published var showMenu: Bool
private var environment: Environment
private var cancellables = Set<AnyCancellable>()
init(environment: Environment) {
_showMenu = .init(initialValue: environment.showMenu)
environment.$showMenu
.receive(on: DispatchQueue.main)
.sink(receiveValue: { [weak self] value in
self?.showMenu = value
})
.store(in: &cancellables)
}
}
You can also use other forms of Dependency Injection to inject the Environment (or even use a singleton).
Generally there are different ways to show your Environment variables (eg. showMenu) in the View (and refresh it):
1) The Environment is injected into your View (NOT to ViewModel) as an #EnvironmentObject - for cases when you need to access the Environment from the View only.
2) The ViewModel subscribes to the Environment (as presented above) and publishes its own variables to the View. No need to use an #EnvironmentObject in your View then.
3) The Environment is injected into your View as an #EnvironmentObject and then is passed to the ViewModel.