Using UIViewController via the SwiftUI Environment

ContentView.swift

//
//  ContentView.swift
//  TestSwiftUI1
//
//

import SwiftUI

struct ContentView: View {
	@Environment(\.viewController) private var viewControllerHolder: UIViewController?
	private var viewController: UIViewController? {
		self.viewControllerHolder
	}
    var body: some View {
		Button("Show Modal") {
			self.viewController?.present(style: .fullScreen) {
				ModalView(title: "Sweet!", subtitle: "full screen?")
			}
		}
    }
}

struct ModalView: View {
	@Environment(\.viewController) private var viewControllerHolder: UIViewController?

	let title: String
	let subtitle: String
	var body: some View {
		VStack(spacing: 20) {
			Text(title).font(.largeTitle)
			Text(subtitle).font(.title).foregroundColor(.gray)
			Text("By changing the State var you can trigger the sheet to show")
				.frame(maxWidth: .infinity)
				.padding().font(.title).layoutPriority(1)
				.background(Color.red).foregroundColor(.white)
			Spacer()
			Button("Dismiss") {
				self.viewControllerHolder?.dismiss(animated: true, completion: nil)
			}
			.accentColor(.red)
		}
	}
}

struct ContentView_Previews: PreviewProvider {
    static var previews: some View {
        ContentView()
    }
}

UIViewController+SwiftUI.swift

//
//  UIViewController+SwiftUI.swift
//
//  Created by Timothy Costa on 2019/07/04.
//  Modified (fixed) by Dad 2019.11.16
//  Copyright © 2019 timothycosta.com. All rights reserved.
//  from his gist here: https://gist.github.com/timothycosta/a43dfe25f1d8a37c71341a1ebaf82213
//  which he referenced in a StackOverflow post here: https://stackoverflow.com/a/56880640/145108
//

import SwiftUI

struct ViewControllerHolder {
	weak var value: UIViewController?
}

struct ViewControllerKey: EnvironmentKey {
	static var defaultValue: ViewControllerHolder { return ViewControllerHolder(value: UIApplication.shared.windows.first?.rootViewController ) }
}

extension EnvironmentValues {
	var viewController: UIViewController? {
		get { return self[ViewControllerKey.self].value }
		set { self[ViewControllerKey.self].value = newValue }
	}
}

extension UIViewController {
	func present<Content: View>(style: UIModalPresentationStyle = .automatic, @ViewBuilder builder: () -> Content) {
		let toPresent = UIHostingController(rootView: AnyView(EmptyView()))
		toPresent.modalPresentationStyle = style
		toPresent.rootView = AnyView(
			builder()
				.environment(\.viewController, toPresent)
		)
		self.present(toPresent, animated: true, completion: nil)
	}
}

Note this comment on the SO post:

To dismiss the ViewController I pass it to my View and then call self.vc?.dismiss(animated: true, completion: {}) but I have the suspicion that this still keeps something in memory because when I call this again and then trigger an update on a Publisher and catch it via onReceive() it gets called as often as I've opened and dismissed the ViewController any thoughts? – krjw Oct 17 at 17:01