Create user
-------------
Auth.auth().createUser(withEmail: "user@email.com", password: "PASSWORD******") { (user, error) in
    if let error = error {
        print(error.localizedDescription)
    }
    else if let user = user {
        print("Sign Up Successfully. \(user.uid)")
    }
}
---------------------
Login
---------------------
Auth.auth().signIn(withEmail: "user@email.com", password: "PASSWORD******") { (user, error) in
    if let error = error {
        print(error.localizedDescription)
    }
    else if let user = user {
        print(user.uid)
    }
}
------------------------
SignOut
------------------------

if Auth.auth().currentUser != nil {
    do {
        try Auth.auth().signOut()
    }
    catch {
    }
}
-------------------------
show New VC if Succss Login or Create User
-------------------------
1- add New Id to New VC Storybode `ID "Home"
2- add the Code
   print("Sign Up Successfully")
                let viewController:UIViewController = UIStoryboard(name: "Main", bundle: nil).instantiateViewController(withIdentifier: "Home")
                self.present(viewController, animated: true, completion: nil)

        -------------------------
        3- Code To Remember

        -----------

        import UIKit
import Firebase
import FirebaseAuth

class ViewController: UIViewController {
    @IBOutlet weak var email: UITextField!
    @IBOutlet weak var password: UITextField!

    override func viewDidLoad() {
        super.viewDidLoad()

    }

    @IBAction func Login(_ sender: Any) {
        Auth.auth().createUser(withEmail: email.text!, password: password.text!) { (user, error) in
            if let error = error {
                print(error.localizedDescription)

            }
            else if let user = user {
                print("Sign Up Successfully")
                let viewController:UIViewController = UIStoryboard(name: "Main", bundle: nil).instantiateViewController(withIdentifier: "Home")
                self.present(viewController, animated: true, completion: nil)
            }
        }
    }

}