Unable to share environment between Views - swiftui

Question

Environment: Xcode Version 11.0 beta 4 (11M374r)
I'm unable to share the 'environment' with a second view.
I've instantiate the environment BindableObject in the SceneDelegate:
SceneDelegate.swift:
I'm using #EnvironmentObject in both the base (ContentView) and the detail view.
The environment has already been set up in the SceneDelegate so it should be available to all views.
The ContentView does see the environment.
But DetailView blows up:
Here's the complete code:
import Combine
import SwiftUI
struct UserInfo {
var name: String
var message: String
init(name: String, msg: String) {
self.name = name; self.message = msg
}
}
// A BindableObject is always a class; NOT a struct.
class UserSettings: BindableObject {
let willChange = PassthroughSubject<Void, Never>()
var userInfo = UserInfo(name: "Ric", msg: "Mother had a feeling, I might be too appealing.") {
didSet {
willChange.send()
}
}
}
// =====================================================================================================
struct DetailView: View {
#Binding var dismissFlag: Bool
#EnvironmentObject var settings: UserSettings // ...<error source>
var body: some View {
VStack {
Spacer()
Button(action: dismiss) {
Text("Dismiss")
.foregroundColor(.white)
}
.padding()
.background(Color.green)
.cornerRadius(10)
.shadow(radius: 10)
Text("Hello")
Spacer()
}
}
private func dismiss() {
settings.userInfo.message = "Rubber baby buggy bumpers."
dismissFlag = false
}
}
// ---------------------------------------------------------------------------
// Base View:
struct ContentView: View {
#State var shown = false
#EnvironmentObject var settings: UserSettings
var body: some View {
VStack {
Spacer()
Button(action: {
self.settings.userInfo.name = "Troglodyte"
self.settings.userInfo.message = "Top Secret"
self.shown.toggle()
}) {
Text("Present")
.foregroundColor(.white)
}.sheet(isPresented: $shown) { DetailView(dismissFlag: self.$shown) }
.padding()
.background(Color.red)
.cornerRadius(10)
.shadow(radius: 10)
Text(self.settings.userInfo.message)
Spacer()
}
}
}
// =====================================================================================================
#if DEBUG
struct ContentView_Previews: PreviewProvider {
static var previews: some View {
ContentView()
}
}
#endif
What am I missing?
What am I doing wrong?
Revision per suggestion:
import SwiftUI
import UIKit
class SceneDelegate: UIResponder, UIWindowSceneDelegate {
var window: UIWindow?
var userSettings = UserSettings()
func scene(_ scene: UIScene, willConnectTo session: UISceneSession, options connectionOptions: UIScene.ConnectionOptions) {
// Use a UIHostingController as window root view controller
if let windowScene = scene as? UIWindowScene {
let window = UIWindow(windowScene: windowScene)
window.rootViewController = UIHostingController(rootView: ContentView().environmentObject(userSettings))
self.window = window
window.makeKeyAndVisible()
}
}
}
His the runtime-error message after modifying the SceneDelegate:
Here's a clue:

Answer 1

In SceneDelegate you need to declare an instance of your variable:
var userSettings = UserSettings() // <<--- ADD THIS
func scene(_ scene: UIScene, willConnectTo session: UISceneSession, options connectionOptions: UIScene.ConnectionOptions) {
if let windowScene = scene as? UIWindowScene {
let window = UIWindow(windowScene: windowScene)
window.rootViewController = UIHostingController(rootView: ContentView()
.environmentObject(userSettings) <<-- CHANGE THIS
)
self.window = window
window.makeKeyAndVisible()
}
}
That creates a global/environment instance of userSettings.
EDIT:
There's a second error happening, related to exposing your #EnvironmentObject to the preview. Per this answer by #MScottWaller, you need to create an separate instance in both SceneDelegate and PreviewProvider.
#if DEBUG
struct ContentView_Previews : PreviewProvider {
static var previews: some View {
ContentView().environmentObject(UserSettings())
}
}
#endif