ARKit camera tracking state can’t show on SwiftUI - swift

Question

I’m trying to show the camera tracking state info on top of device screen, but still get errors for all my efforts. I’m very confused with how ARView works with SwiftUI, for showing AR experience and adding button icons on top of it is simple, but to getting data from session just looks more work need to be done, could someone help me this? Thanks!
Error in ViewModel: ‘description is a get-only property’
Content View
import SwiftUI
import ARKit
import RealityKit
struct ContentView: View {
#StateObject var vm = ViewModel()
var body: some View {
ZStack{
ARViewContainer()
.edgesIgnoringSafeArea(.all)
.environmentObject(vm)
VStack{
Text(vm.sessionInfoLabel)
.font(.title3)
.foregroundColor(.red)
Spacer()
HStack{
Button{
} label: {
Image(systemName: "person.2")
.padding()
.font(.title)
}
Spacer()
Button{
} label: {
Image(systemName: "target")
.padding()
.font(.title)
}
}
.padding()
}
}
}
}
struct ARViewContainer: UIViewRepresentable {
#EnvironmentObject var vm: ViewModel
func makeUIView(context: Context) -> ARView {
return vm.arView
}
func updateUIView(_ uiView: ARView, context: Context) {
}
}
ViewModel
import SwiftUI
import ARKit
import RealityKit
class ViewModel: ObservableObject {
#Published var arView: ARView
var sessionInfoLabel = ""
init() {
arView = ARView.init(frame: .zero)
let config = ARWorldTrackingConfiguration()
config.planeDetection = .horizontal
arView.session.delegate = arView
arView.session.run(config)
}
}
extension ARView: ARSessionDelegate {
public func session(_ session: ARSession, cameraDidChangeTrackingState camera: ARCamera) {
camera.trackingState.description = ViewModel().sessionInfoLabel
}
}
extension ARCamera.TrackingState: CustomStringConvertible {
public var description: String {
switch self {
case .normal:
return "Normal"
case .notAvailable:
return "Not Available"
case .limited(.initializing):
return "Initializing"
case .limited(.excessiveMotion):
return "Excessive Motion"
case .limited(.insufficientFeatures):
return "Insufficient Features"
case .limited(.relocalizing):
return "Relocalizing"
case .limited:
return "Unspecified Reason"
}
}
}