Performing two authentication commands only if neither fail in Swift - swift

Question

I am trying to register a user in Firebase, AND add that user to a "users" collection with additional fields. When registering a user, I only want these commands to execute if BOTH of them are successful. For example, I don't want to register a user in Firebase if the user fails to be added to the users collection. But I also don't want the user to be added to the users collection if the firebase createUser function fails.
func register(withEmail email: String, password: String, fullname: String, username: String) {
Auth.auth().createUser(withEmail: email, password: password) { [self] result, error in
if let error = error {
print("Failed to register with error \(error.localizedDescription)")
return
}
guard let user = result?.user else { return }
let data = ["email": email,
"username": username.lowercased(),
"fullname": fullname,
"uid": user.uid,
"listOfUserActions": listOfUserActions]
Firestore.firestore().collection("users")
.document(user.uid)
.setData(data) { _ in
self.didAuthenticateUser = true
}
}
}
The way I have this set up right now, if the user was added to FirebaseAuth but the post to "users" failed, wouldn't this just break the app if I have functionality depending on the "users" collection?

Answer 1

You may use a combination of the methods from the createUser and setData methods to make sure that both of those operations succeed before setting didAuthenticateUser to true.
Here's the modified code:
func register(withEmail email: String, password: String, fullname: String, username: String) {
Auth.auth().createUser(withEmail: email, password: password) { [self] result, error in
if let error = error {
print("Failed to register with error \(error.localizedDescription)")
return
}
guard let user = result?.user else { return }
let data = ["email": email,
"username": username.lowercased(),
"fullname": fullname,
"uid": user.uid,
"listOfUserActions": listOfUserActions]
Firestore.firestore().collection("users")
.document(user.uid)
.setData(data) { error in
if let error = error {
print("Failed to set data with error \(error.localizedDescription)")
return
}
self.didAuthenticateUser = true
}
}
}