manually managing special view's ID

sample-view-model-init.swift

import SwiftUI

@main
struct WindowPresentationFunApp: App {
    @State var appState = AppState()

    var body: some Scene {
        WindowGroup {
            RootView(appState: appState)
                .onAppear {
                    DispatchQueue.main.asyncAfter(deadline: .now() + .seconds(1)) {
                        appState.show = true
                    }
                }
        }
    }
}

struct RootView: View {
    var appState: AppState

    var body: some View {
        ZStack {
            SpecialView()
                .id(appState.specialViewID)

            if appState.show {
                Text("Some cool text")
            }
        }
    }
}

struct SpecialView: View {
    @State var viewModel = ViewModel()

    var body: some View {
        Text("Special stuff")
    }
}

@Observable class AppState {
    var show: Bool = false {
        didSet {
            specialViewID = UUID()
        }
    }

    var specialViewID = UUID()
}

@Observable class ViewModel {
    init() {
        print("✅ View model was inited")
    }

    deinit {
        print("❌ View model was deinited")
    }
}

By the way, I tested this on macOS with multiple windows. I think you probably want to initialize AppState once per window. Initially I thought all you'd have to do is move AppState to RootView, but that actually didn't have an effect. I followed this tip to initialize it an onAppear. It works, but feels like a hacky workaround that shouldn't be necessary. 🤷‍♂️

import SwiftUI

@main
struct WindowPresentationFunApp: App {
    var body: some Scene {
        WindowGroup {
            RootView()
        }
    }
}

struct RootView: View {
    @State var appState: AppState?

    var body: some View {
        ZStack {
            if let appState {
                SpecialView()
                    .id(appState.specialViewID)

                if appState.show {
                    Text("Some cool text")
                }
            }
        }
        .onAppear {
            appState = AppState()

            DispatchQueue.main.asyncAfter(deadline: .now() + .seconds(1)) {
                appState?.show = true
            }
        }
    }
}

struct SpecialView: View {
    @State var viewModel = ViewModel()

    var body: some View {
        Text("Special stuff")
    }
}

@Observable class AppState {
    var show: Bool = false {
        didSet {
            specialViewID = UUID()
        }
    }

    var specialViewID = UUID()

    init() {
        print("✅ App state was inited")
    }

    deinit {
        print("❌ App state was deinited")
    }
}

@Observable class ViewModel {
    init() {
        print("✅ View model was inited")
    }

    deinit {
        print("❌ View model was deinited")
    }
}