Firebase And Firestore User management in SwiftUI - firebase

Question

I want to build an app that handles authentication with firebase and the cloud storage part with Firestore. How should I automatically create a user inside the "users" collection when I a user registers and also how should the user struct fetching be done when the user just logged in the app.
I insert only the functions
I have a class authenticationViewModel:
ObservableObject{
#Published var user:User?
func SignInWithEmailAndPassword() async -> Bool {
//login user account
authenticationState = .Authenticating
do{
let authResult = try await Auth.auth().signIn(withEmail: email, password: password)
print("User \(authResult.user.uid) signed in")
}
catch{
print(error)
errorMessage = error.localizedDescription
authenticationState = .UnAuthenticated
return false
}
authenticationState = .Authenticated
errorMessage=""
return true
}
func SignUpwithEmailAndPassword() async -> Bool {
//create new user account
authenticationState = .Authenticating
do{
let authResult = try await Auth.auth().createUser(withEmail: email, password: password)
print("User \(authResult.user.uid) signed in")
}
catch{
print(error)
errorMessage = error.localizedDescription
authenticationState = .UnAuthenticated
return false
}
authenticationState = .Authenticated
errorMessage=""
return true
}
}
and a class called userDataManagment:
ObservableObject{
#Published var sessionUser: CustomUser?
init(){
getUserData(documentID: Auth.auth().currentUser?.uid ?? "")
}
func getUserData(documentID: String){
let docRef=db.collection("users").document(documentID)
docRef.getDocument(as: CustomUser.self){ result in
switch result{
case.success(let user):
//User was succsesfully initialized
self.sessionUser = user
self.errorMessage = nil
case.failure(let error):
//user could not be instantieted
self.errorMessage="Error decoding document: \(error.localizedDescription)"
}
}
}
func updateUserData(user: CustomUser){
if let id=user.id{
let docRef=db.collection("user").document(id)
do{
try docRef.setData(from: user)
}catch{
print(error)
}
}
}
func addUser(user: User){
let collectionRef=db.collection("users")
do{
let newDocReference = try collectionRef.addDocument(from: self.sessionUser)
print("User was added succseully")
}catch{
print(error)
}
}
}
I couldn't figure out how to properly manage this situation so for now I'm just using a testUser that is hardCoded so that I can create the proper views for my app