I got it thanks to Claude31. import SwiftUI struct ContentView: View { @ObservedObject var monster: Monster var body: some View { VStack { Button { monster.items.append(Keyword()) } label: { Text("Add me!") }.padding(.vertical, 10.0) ForEach(monster.items) { item in KeywordRow(id: item.id).environmentObject(monster) } } } } struct Keyword: Identifiable { let id = UUID() } struct KeywordRow: View { @State var id = UUID() @EnvironmentObject var monster: Monster var body: some View { VStack { HStack { Text("ID: \(id)") Button { monster.items.removeAll(where: { $0.id == id} ) } label: { Text("Delete") } } } } }

I guess the user State object in ContentView comes with default values.

import SwiftUI struct ContentView: View { @EnvironmentObject var gameSettings: GameSettings var body: some View { GeometryReader { geo in ZStack { HStack(spacing: 0.0) { RightView().environmentObject(gameSettings) .frame(width: geo.size.width / 2.0, height: geo.size.height) Spacer() } VStack { HStack { Spacer() Button { print("\(gameSettings.score)") } label: { Text("Print") .font(.largeTitle) }.padding(.trailing, 40.0) } Spacer() } } } } }

I guess I've solved a problem on my own again. import SwiftUI struct ContentView: View { @StateObject var monster = MonsterObservable.shared var body: some View { GeometryReader { geo in ZStack { HStack(spacing: 0.0) { RightView() .frame(width: geo.size.width, height: geo.size.height) } ShowDialogView(isShowing: $monster.showDialog) { } .frame(width: 500, height: 600, alignment: .center) .cornerRadius(10.0) } } } } struct ShowDialogView<Content: View>: View { @Binding var isShowing: Bool @ViewBuilder let content: () -> Content var body: some View { Group { if isShowing { ZStack { Color.brown VStack { Spacer() Button { isShowing = false } label: { Text("Close me") .font(.largeTitle) }.padding([.top, .bottom], 100.0) } } } } } } class MonsterObservable: ObservableObject { static let shared = MonsterObservable() @Published var showDialog = false } class GameScore: ObservableObject { static let shared = GameScore() @Published var score = 0 } struct RightView: View { @ObservedObject var monster = MonsterObservable.shared var body: some View { ZStack { Color.red Button { monster.showDialog = true } label: { Text("Change") .font(.largeTitle) } } } }

I guess I've solved my question as follows. import SwiftUI struct ContentView: View { @ObservedObject var monster: MonsterObservable var body: some View { GeometryReader { geo in ZStack { HStack(spacing: 0.0) { LeftView() .frame(width: geo.size.width / 2.0, height: geo.size.height, alignment: .leading) RightView(showMe: $monster.showDialog) .frame(width: geo.size.width / 2.0, height: geo.size.height, alignment: .trailing) } ShowDialogView(isShowing: monster.showDialog) { } .frame(width: 500, height: 600, alignment: .center) .cornerRadius(10.0) } } } } class MonsterObservable: ObservableObject { @Published var showDialog = false } import SwiftUI struct RightView: View { @Binding var showMe: Bool var body: some View { ZStack { Color.red Button { showMe = true } label: { Text("Tap me") .font(.largeTitle) } } } }

It's trivial as follows. import SwiftUI struct LeftView: View { var body: some View { ZStack { Color.green } } }

I guess I've somehow worked it out as follows. import SwiftUI struct ContentView5: View { @State private var larger = true var body: some View { VStack { Circle() .fill(Color.pink) .frame(width: 150, height: 150) .scaleEffect(larger ? 2 : 1) .animation(.easeInOut(duration: 1).repeatForever(), value: larger) }.onAppear { larger = false } } }

I've figured it out. You use UIApplicationDelegateAdaptor for iOS, NSApplicationDelegateAdaptor for Cocoa. import SwiftUI @main struct MyCrazyApp: App { @UIApplicationDelegateAdaptor(AppDelegate.self) var appDelegate var body: some Scene { WindowGroup { ContentView() } } } class AppDelegate: UIResponder, UIApplicationDelegate { let fileManager = FileManager.default } In this fashion, you will access to fileManager in AppDelegate inside another View.

HStack + Spacer() should work unless you have NavigationLink inside the list.

The availability of UIStepper in Mac Catalyst depends on the deployment target. According to the doc, it requires iOS 13.0 or higher.

I've ended up creating a UIViewRepresentable struct so that I can set an NSAttributedString object to a UILabel object.

I've solved both of the issues with the following. struct PickColorView: View { @State var numberIndex: Int = 4 @State var textSizeIndex: Int = 0 let numbers: [Int] = [14, 16, 18, 20, 22, 24, 26, 28, 30, 32, 34, 36, 38, 40, 42, 44, 46, 48, 50, 52, 54, 56, 58, 60] var body: some View { NavigationView { Form { Picker(selection: $numberIndex, label: Text("Numbers")) { ForEach((0...20), id: \.self) { Text("\($0)") } }.onChange(of: numberIndex) { newIndex in print("Index: \(newIndex)") } Picker("Numbers", selection: $textSizeIndex) { ForEach(0..<numbers.endIndex) { index in let number = numbers[index] Text("\(number)") } }.onChange(of: textSizeIndex) { newIndex in print("Index: \(newIndex)") } } .navigationBarTitle("Settings") .navigationBarHidden(false) } .navigationViewStyle(StackNavigationViewStyle()) } }

You can do it if you hide the title bar.

I've figured out a way of doing it with StateObject. It's something like the following. import SwiftUI import Combine struct ContentView2: View { @State var disabled: Bool = false @StateObject var delayMonitor = DelayMonitor() @State private var showingAlert = false var body: some View { VStack { Spacer() Button("Tap to connect me") { disabled = true delayMonitor.start() } .font(.system(size: 24.0)) .disabled(disabled) Spacer() .frame(height: 30.0) }.onChange(of: delayMonitor.failed) { newValue in print("You've failed?: \(newValue)") disabled = !newValue showingAlert = newValue } .alert("Something is wrong...", isPresented: $showingAlert) { Button("OK", role: .cancel) { } } } } class DelayMonitor: ObservableObject { var timer = Timer() var seconds: Double = 0.0 @Published var failed: Bool = false func start() { timer = Timer.scheduledTimer(withTimeInterval: 1.0, repeats: true, block: { _ in self.seconds += 1.0 if self.seconds == 5.0 { // arbitrary timeout self.timer.invalidate() DispatchQueue.main.async() { [weak self] in guard let strongSelf = self else { return } strongSelf.failed = true } } }) } } The onChange guy will let me know only if the value (delayMonitor.failed) has changed. Since its initial value is set to false, I'll get a call only if it changes to true.

I guess ObservableObject is a ticket to using Combine in SwiftUI. So I can write the following. import SwiftUI import Combine struct ContentView: View { @State var cancellables = Set<AnyCancellable>() @StateObject var login = Login() @State var canSave: Bool = false var body: some View { VStack { Text("Login") TextField("Enter username", text: $login.user) TextField("Enter password", text: $login.pass) Button("Save") { } .foregroundColor(canSave ? Color.orange : Color.gray) .font(.system(size: 40.0)) .disabled(!canSave) } .padding(.horizontal, 40.0) .onAppear { Publishers.CombineLatest(login.$user, login.$pass) .sink { completion in print(completion) } receiveValue: { (result0, result1) in let bool = (result0.count > 3 && result1.count > 3) canSave = bool }.store(in: &cancellables) } } } class Login: ObservableObject { @Published var user: String = "" @Published var pass: String = "" } This is really good stuff.