Need Help Maintaining Swift Environment Object - ios

Question

Trying to place a SwiftUI View into a ViewController using UIHostingController, but receiving the following error:
No ObservableObject of type UIStateModel found. A View.environmentObject(_:) for UIStateModel may be missing as an ancestor of this view.
All help appreciated, I've been quite stuck :(.
ViewController.swift
class ViewController: UIViewController {
#EnvironmentObject var UIModel: UIStateModel
var uiState: UIStateModel = UIStateModel()
override func viewDidLoad() {
super.viewDidLoad()
addCarousel()
}
func addCarousel(){
let snapC : SnapCarousel
let contentView : UIHostingController<SnapCarousel>
uiState = UIStateModel()
snapC = SnapCarousel( UIState: uiState )
contentView = UIHostingController(rootView: snapC)
addChild(contentView)
view.addSubview(contentView.view)
contentView.didMove(toParent: self)
}
}
Carousel.swift
struct SnapCarousel: View {
var UIState: UIStateModel
//Carousel instantiation
}
struct Card: Decodable, Hashable, Identifiable {
//code
}
public class UIStateModel: ObservableObject {
#Published var activeCard: Int = 0
#Published var screenDrag: Float = 0.0
}
struct Carousel<Items : View> : View {
#EnvironmentObject var UIState: UIStateModel
//card management
}
struct Canvas<Content : View> : View {
// view manager
}
struct Item<Content: View>: View {
#EnvironmentObject var UIState: UIStateModel
//code for card view
}

Answer 1

You need to register UIStateModel as an #EnvironmentObject so that it can be injected automatically in the subviews.
First, update SnapCarousel to hold the environmentObject:
struct SnapCarousel: View {
#EnvironmentObject var UIState: UIStateModel
//Carousel instantiation
}
To register model as environment object, when register with SnapCarousel as:
let snapC = SnapCarousel()
snapC.environmentObject(uiState)
If you don't need a reference to uiState, you can simplify the whole thing to:
class ViewController: UIViewController {
override func viewDidLoad() {
super.viewDidLoad()
addCarousel()
}
func addCarousel() {
let controller = UIHostingController(rootView: SnapCarousel().environmentObject(UIStateModel()))
addChild(controller)
view.addSubview(controller.view)
controller.didMove(toParent: self)
// add some constraints to fill the parent view
NSLayoutConstraint.activate([
controller.view.widthAnchor.constraint(equalTo: view.widthAnchor),
controller.view.heightAnchor.constraint(equalTo: view.heightAnchor),
controller.view.centerXAnchor.constraint(equalTo: view.centerXAnchor),
controller.view.centerYAnchor.constraint(equalTo: view.centerYAnchor)
])
}
}