UIAlertController and input validation I'm refactoring some "old" Swift code using deprecated UIAlertView and delegates.

I have a UIAlertController with an input textfield inside (and two buttons, OK and CANCEL). The user should insert his email address, then I should validate it anytime he enters a character: when the mail address is valid, the UIAlertController button is enabled, else is disabled.

I got this code perfectly working but for some reason I'm not very happy with this solution. Is there something you would change?

var alertTextField: UITextField!

func textFieldDidChange(){

    if let e = alertTextField.text {
        let alertButton = alertController.actions[0]
        alertButton.isEnabled = !Utils.isValidEmail(testStr: e) ? false : true
    }
}

var alertController = UIAlertController(title: "Insert your email", message: "message", preferredStyle: .alert)


@IBAction func passwordForgot(_ sender: Any) {

    let ok = UIAlertAction(title: "OK", style: .default, handler: { (action) -&gt; Void in
        print("Ok Button was Pressed")
    })
    ok.isEnabled = false

    let cancel = UIAlertAction(title: "Cancel", style: .cancel) { (action) -&gt; Void in
        print("Cancel Button was Pressed")
    }

    alertController.addAction(ok)
    alertController.addAction(cancel)

    alertController.addTextField { (textField) -&gt; Void in
        self.alertTextField = textField
        self.alertTextField?.placeholder = "mail"
        textField.addTarget(self, action: #selector(self.textFieldDidChange), for: UIControlEvents.editingChanged)
    }

    self.present(alertController, animated: true, completion: nil)

}
I would change this:

alertButton.isEnabled = !Utils.isValidEmail(testStr: e) ? false : true


to this one:

alertButton.isEnabled = Utils.isValidEmail(testStr: e)