SwiftUI - NavigationView - Deep Link

DeepLink.swift

import Combine
import SwiftUI

extension EnvironmentValues {
    var deepLink: DeepLink {
        get {
            self[DeepLink.self]
        }
        set {
            self[DeepLink.self] = newValue
        }
    }
}

struct DeepLink: EnvironmentKey {
    let showB = CurrentValueSubject<Bool, Never>(false)
    let showC = CurrentValueSubject<Bool, Never>(false)

    static let defaultValue = DeepLink()

    func presentB() {
        showB.send(true)
    }

    func presentBC() {
        showB.send(true)
        showC.send(true)
    }

    func presentC() {
        showC.send(true)
    }
}

struct Lazy<Content: View>: View {
    private let builder: () -> Content

    init(_ builder: @escaping () -> Content) {
        self.builder = builder
    }

    var body: Content {
        builder()
    }
}

struct A: View {
    @Environment(\.deepLink) var deepLink

    @State var isBActive: Bool = false

    var body: some View {
        NavigationView {
            VStack {
                Spacer()

                Button(action: { self.deepLink.presentB() }) {
                    Text("Go to B")
                }

                Spacer()

                //
                // iOS < 13.4 -> presents B, presents C and pops C immediately
                // iOS = 13.4 -> works as expected, presents B, presents C
                //
                Button(action: { self.deepLink.presentBC() }) {
                    Text("Go to B & C")
                }

                Spacer()

                NavigationLink(destination: Lazy { B() }, isActive: $isBActive) {
                    EmptyView().hidden()
                }
                .onReceive(deepLink.showB) { show in
                    print("A received showB(\(show))")
                    self.isBActive = show
                }
            }
            .navigationBarTitle("A")
        }
    }
}

struct B: View {
    @Environment(\.deepLink) var deepLink

    @State var isCActive: Bool = false {
        willSet {
            print("willSet(isCActive): \(isCActive) -> \(newValue)")
        }
        didSet {
            print("didSet(isCActive): \(isCActive)")
        }
    }

    var body: some View {
        VStack {
            Button(action: { self.deepLink.presentC() }) {
                Text("Go to C")
            }

            NavigationLink(destination: Lazy { C() }, isActive: $isCActive) {
                EmptyView().hidden()
            }
            .onReceive(deepLink.showC) { show in
                print("B received showC(\(show))")
                self.isCActive = show
            }
        }
        .navigationBarTitle("B")
    }
}

struct C: View {
    var body: some View {
        VStack {
            Text("Stay, please, stay and don't pop!")
        }
        .navigationBarTitle("C")
    }
}