Use a Snap value in firebase

Question

here is my situation for my iOS app ( I am using swift 3.0 and firebase).

I have a login screen, where the user are able to login via their E-mail using the Auth of firebase. For that I am using this code:

    @IBAction func signInButtonPressed(_ sender: UIButton)
{


    if let email = emailField.text, let password = passwordField.text
    {
      //  FIRDatabase.database().reference().child("users").child(self.emailField.text!).observeSingleEvent(of: .value, with: {(userEmail) in
       // FIRAuth.auth()?.signIn(withEmail: email, password: password)

        FIRAuth.auth()?.signIn(withEmail: email, password: password)
        {
            (user, error) in

            if let error = error
            {
                let alertController = UIAlertController(title: "Login or password incorrect", message:
                    "", preferredStyle: UIAlertControllerStyle.alert)
                alertController.addAction(UIAlertAction(title: "OK", style: UIAlertActionStyle.default,handler: nil))

                self.present(alertController, animated: true, completion: nil)                }
            else
            {
                print("AUTH: EMAIL AUTH SUCCESSFUL")

                User.currentUserId = user?.uid
                User.startTrackingCurrentUser()
                self.performSegue(withIdentifier: "ToFeed", sender: nil)
            }
        }
    }
}

Which is working perfectly !

What I'am trying to achieve, is instead to sign in user via their username. For that I believe the best thing is when recognising if the user exist, to send the email value instead - fetching the data from the DB.

My DB is configure correctly, and fetch the auth system such as:

--name of db
----posts
----users
------username
------email
------id

And I get the user recognise in my console when typing the correct username in the text field via:

@IBAction func textFieldEditingDidChange(_ sender: Any) {
    FIRDatabase.database().reference().child("users").child(self.emailField.text!).observeSingleEvent(of: .value, with: {(email) in

    if let userDict = email.value as? [String:AnyObject]{
        for each in userDict{
            let email = each.1 as! String
        }
    }

    if email.exists(){

        print(email)

    }else{

        print("USER NOT EXIST")

    }

})

}

I'm having display in my console the following when the username written is correct:

Snap (myuser) {
username = myuser;
email = "myemail@email.com";
id = 8mbwXUMe0Ye4ip2mhhvEySxmxiI5;

}

For this I have been following this thread:

Sign In by UserName : Firebase,Swift

From now, how can i on submit, use the email value from the snap instead of the username to be able to login ? I don't manage to make this work, I have been working on that for a week now . . .

Any help will be superb ! I'm starting on iOS Dev.

Thanks a lot !

---EDIT --

Now I'm managing to have only the email try print in my console via:

IBAction func textFieldEditingDidChange(_ sender: Any) {


    FIRDatabase.database().reference().child("users").child(self.emailField.text!).observeSingleEvent(of: .value, with: {(email) in

        if let userDict = email.value as? [String:AnyObject]{
   print(email)

        }

        if email.exists(){


        }else{

            print("USER NOT EXIST")

        }

    })
}

But still looking how to pass the value ?

Answer 1

You should get this email from snapshot and use it in signIn function:

FIRAuth.auth()!.signIn(withEmail: email, // your fetched email
                         password: userPassword.text!) { // userPassword is UITextField
                          user, error in
                          if error != nil {
                             // here process your error like
                             self.errorLabel.text = "Wrong login or password!"
                             print("\(String(describing: error?.localizedDescription))")
                          } else {
                             // you have signed in. Go to next controller
                             self.performSegue(withIdentifier: "fromLoggedInToTabBar", sender: self)
                          }
  }

Hope it helps

Answer 2

I want to stress that creating a username login system is strongly discouraged!

Let's start with a users node

user_email_lookup
  uid_0
    email: "johnny@dontdothis.com"
    user_name: "johnny_unsecure"
  uid_1
    email: "fred@exposednodes.com"
    user_name: "fred_stolendata"

the user_email_lookup node will provide the link between the user name the user entered and the email address of an authenticated user in Firebase. This node needs to have rules that allow anyone to access it - this is necessary as the queries on that node need to be done by an unauthenticated user. There's another structure option as well

user_email_lookup
  johnny_unsecure: "johnny@dontdothis.com"
  fred_stolendata: "fred@exposednodes.com"

But it will make managing user name and/or email changes later more difficult, so not recommended.

(again, don't do this, it's bad form)

Here are the base rules that need to apply the user_email_lookup

{
    "rules": {
        ".read": true,
        ".write": true
    }
}

(ugh; remember this node can be accessed by anyone. Don't do it!)

Assume that the app presents a screen where the user can type their user name and password, with a login button. Pressing the login button calls the beginLogin function as follows

func beginLogin() {
    let userName = "johnny_unsecure" //from the userNameField.text
    let password = "my_password" // from the passwordField.text

    let lookupRef = self.ref.child("user_email_lookup")
    let queryRef = lookupRef.queryOrdered(byChild: "user_name").queryEqual(toValue: userName)

    queryRef.observeSingleEvent(of: .childAdded, with: { snapshot in
        let dict = snapshot.value as! [String: Any]
        let email = dict["email"] as! String
        self.logUserIn(email: email, password: password)
    })
}


func logUserIn(email: String, password: String) {

    Auth.auth().signIn(withEmail: email, password: password, completion: { (user, error) in 
        if error != nil {
            let err = error?.localizedDescription
            print(err)
        } else {
            print("succesfully authd")
            print(user)
        }
    })
}