@IBAction func createAccount(sender: AnyObject) {

    var username = usernameField.text
    var email = emailField.text
    var password = passwordField.text
    if username != "" && email != "" && password != "" {
        FIRAuth.auth()?.createUserWithEmail(email!, password: password!, completion: { (user, error) in
            databaseRef.child("users/(user.uid)/username").setValue(username)
            databaseRef.child("users/(user.uid)/password").setValue(password)
            databaseRef.child("users/(user.uid)/uid").setValue(user?.uid)
        })
    } else {
        print("please complete all fields")
    }
}

@IBAction func createAccount(sender: AnyObject) {

    var username = usernameField.text
    var email = emailField.text
    var password = passwordField.text

    if username != "" && email != "" && password != "" {

        FIRAuth.auth()?.createUserWithEmail(email!, password: password!, completion: { (user, error) in

             if let user = FIRAuth.auth()?.currentUser {

                databaseRef.child("users/(user.uid)/username").setValue(username)
                databaseRef.child("users/(user.uid)/password").setValue(password)
                databaseRef.child("users/(user.uid)/email").setValue(email)

                print(user.uid)

            } else {

                print("no user")

            }

        })


    } else {

        print("please complete all fields")

    }

Auth.auth().createUser(withEmail: email, password: password) { (user, error) in
    // guard against errors and optionals
    guard error == nil else { return }
    guard let user = user else { return }
    let userObject = [
        "uid": user.uid,
        "username": username,
        "password": password, // I don't recommend storing passwords like this by the way
        "email": email
        ] as [String:Any]
    databaseRef.setValue(userObject)
}