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.

I could do something like the following. class ValidateLogin { var good: Bool = false let user: String let pass: String init(user: String, pass: String) { self.user = user self.pass = pass } func validateMe() -> Bool { if user.count > 3 && pass.count > 3 { good = true } return good } } struct ContentView: View { @State var userText: String = "" @State var passText: String = "" @State var canSave: Bool = false var body: some View { ZStack { VStack { TextField("Username", text: $userText) { }.onChange(of: userText) { newValue in let validateLogin = ValidateLogin(user: userText, pass: passText) canSave = validateLogin.validateMe() } SecureField("Password", text: $passText) { }.onChange(of: passText) { newValue in let validateLogin = ValidateLogin(user: userText, pass: passText) canSave = validateLogin.validateMe() } }.padding(.horizontal, 20.0) }.onAppear { //Publishers.CombineLatest($userText, $passText) } } } The code above doesn't involve Combine at all. I want to do it in a Combine way.

I've solved the problem by having NavigationView before ScrollView like the following. ZStack { VStack { NavigationView { ScrollView(.horizontal, showsIndicators: false) { HStack(alignment: .top, spacing: 0) { ForEach(horizonModels, id: \.self) { model in if model.id == 0 { NavigationLink(model.name) { MenuView0() } .font(.system(size: 20.0)) .padding(.horizontal, 20.0) .foregroundColor(Color.white) } else { NavigationLink(model.name) { MenuView1() } .font(.system(size: 20.0)) .padding(.horizontal, 20.0) .foregroundColor(Color.white) } } } } .frame(height: 40.0) .background(Color.orange) } } } That's kind of odd to me.

I've tested my sample app with Apple Sign In with two simulators. They don't go further after I enter my password. When I tested it for a macOS application two weeks ago, I ended up restarting my iMac. The same is true for an iOS sample that I created at the same time. I had to restart my iPhone. Anyway, in your case, I wouldn't be worried as long as it works on an actual device. Some features simply don't work with the simulator.

I guess the following is better. But I'm not completely satisfied. // ViewController // import UIKit import Combine class ViewController: UIViewController { // MARK: - Variables var cancellable: AnyCancellable? private var cancellableSet: Set<AnyCancellable> = [] // MARK: - Life cycle override func viewDidLoad() { super.viewDidLoad() let urlStr = "https://api.github.com/repos/ReactiveX/RxSwift/events" let viewModel = ViewModel(urlStr: urlStr, waitTime: 7.0) viewModel.fetchData(urlText: viewModel.urlStr, timeInterval: viewModel.waitTime) .sink { completion in print("Done!") } receiveValue: { dataModels in print("Count: \(dataModels.count)") } .store(in: &cancellableSet) } } // ViewModel // import UIKit import Combine class ViewModel { var anycancellables = Set<AnyCancellable>() var urlStr: String var waitTime: Double init(urlStr: String, waitTime: Double) { self.urlStr = urlStr self.waitTime = waitTime } func fetchData(urlText: String, timeInterval: Double) -> Future<[DataModel], Error> { return Future<[DataModel], Error> { promise in let url = URL(string: urlText)! var request = URLRequest(url: url) request.timeoutInterval = timeInterval let sessionConfiguration = URLSessionConfiguration.default let session = URLSession(configuration: sessionConfiguration) session.dataTask(with: request) { data, response, error in if let error = error { print("error: \(error.localizedDescription)") promise(.failure("Failure" as! Error)) } if let jsonData = data { do { let dataModels = try JSONDecoder().decode([DataModel].self, from: jsonData) promise(.success(dataModels)) } catch { print("Error while parsing: \(error)") } } }.resume() } } }

I've removed the comment.

The following works. import UIKit import Combine class ViewController: UIViewController { // MARK: - Variables private var cancellableSet: Set<AnyCancellable> = [] override func viewDidLoad() { super.viewDidLoad() let _ = Future<[DataModel], Error> { [weak self] promise in guard let strongSelf = self else { return } let url = URL(string: "https://api.github.com/repos/ReactiveX/RxSwift/events")! URLSession.shared.dataTaskPublisher(for: url) .timeout(2.0, scheduler: DispatchQueue.global(qos: .background)) .retry(3) .map { $0.data } .decode(type: [DataModel].self, decoder: JSONDecoder()) .sink(receiveCompletion: { (completion) in print("I'm done: \(completion)") }, receiveValue: { dataModels in for model in dataModels { print("\(model.id) \(model.type)") } promise(.success(dataModels)) }) .store(in: &strongSelf.cancellableSet) } } } I wonder why it doesn't work if I use ViewModel?

override func viewDidLoad() { super.viewDidLoad() let text = "1:47PM" if let regularFont = UIFont(name: "Helvetica", size: 20.0), let subscriptFont = UIFont(name: "TamilSangamMN", size: 12.0) { let attString:NSMutableAttributedString = NSMutableAttributedString(string: text, attributes: [.font: regularFont]) attString.setAttributes([.font: subscriptFont, .baselineOffset: 6], range: NSRange(location: text.count - 2, length: 2)) label.attributedText = attString } }

You should start by reading the Swift Programming Language.

Call them up?

Don't you have something else to have fun?

Are you having fun?

I guess it goes like the following. Publishers.CombineLatest4($variable0, $variable1, $variable2, $variable3) .combineLatest($variable4) .combineLatest($variable5) .sink { completion in } receiveValue: { response0, response1 in let variable = response0.0 let variable4 = response0.1 let variable5 = response1 let v0 = variable.0 let v1 = variable.1 let v2 = variable.2 let v3 = variable.3 }.store(in: &cancellables) It's kind of odd.

I thought let publishers = Publishers.CombineLatest4($variable0, $variable1, $variable2, $variable3) .combineLatest($variable4) .combineLatest($variable5) could work. But it doesn't.