How to initialize a class using that is using #Binding for an #AppStorage variable - swift

Question

// I am trying to pass in the value of the #AppStorage onto the class using #Binding.
// Declaration of #AppStorge, this the the single source of truth.
// I get the following error on the SigninViewModel = Class 'SigninViewModel' has no initializers
import SwiftUI
struct MainView: View {
#AppStorage("userSignIn") var userSignIn = false
var body: some View {
ZStack {
TabView {
AppointmentsView()
.tabItem {
Image(systemName: "calendar")
Text("Appointments")
}
AccountView(userSignIn: .constant(true))
.tabItem {
Image(systemName: "person")
Text("Profile")
}
StatsView()
.tabItem {
Image(systemName: "chart.bar")
Text("Stats")
}
}
}
}
}
// This the class with the #Binding is being declared and where I am trying to have access to the #AppStorae value.
class SigninViewModel: ObservableObject {
#Published var nonce = ""
#Binding var userSignIn: Bool
func authenticate(credential: ASAuthorizationAppleIDCredential) {
// getting Token...
guard let token = credential.identityToken else {
print("Error with Firebase")
return
}
//Token String...
guard let tokenString = String(data: token, encoding: .utf8) else {
print("Error with Token")
return
}
let firebaseCredential = OAuthProvider.credential(withProviderID: "apple.com",
idToken: tokenString,
rawNonce: nonce)
Auth.auth().signIn(with: firebaseCredential) { (result, err) in
if let error = err {
print(error.localizedDescription)
return
}
// User succesfully logged into Firebase...
print("Logged in Success")
// Directing user to Main page...
withAnimation(.easeInOut) {
self.userSignIn = true
}
}
}
}

Answer 1

You can put the #AppStorage("userSignIn") inside the ObservableObject, but your code quickly becomes a mess.
I think a more simple structure would be to put all of your authentication state inside a single AuthenticationModel: ObservableObject and use it as a #StateObject in the MainView. Additionally, I would recommend pushing it up the view tree.
class AuthenticationModel: ObservableObject {
#Published var nonce = ""
#Published var userSignIn: Bool
init() {
let defaults = UserDefaults.standard
userSignIn = defaults.bool(forKey: "userSignIn")
}
func authenticate(credential: ASAuthorizationAppleIDCredential)
...
// Successful Login
let defaults = UserDefaults.standard
defaults.set(true, forKey: "userSignIn")
// Update the views
userSignIn = true
}
}
struct MainView: View {
#StateObject var authModel: AuthenticationModel = AuthenticationModel()
var body: some View {
if authModel.userSignIn {
Home(authModel: authModel)
} else {
SignIn(authModel: authModel)
}
}
}
struct SignIn: View {
#ObservedObject var authModel: AuthenticationModel
var body: some View {
Button("Sign In") {
authModel.authenticate(...)
}
}
}