How do I observe user editing a textField in an UIAlertController?

Question

I have an UIAlertController with a textField. Since I can't create an outlet for the textField I have to find another way to get ahold of a function that observes user input in realtime.

I have made some attempts, but not successfully. This thread explain how to add a target to the textField:

How do I check when a UITextField changes?

textfield.addTarget(self, action: #selector(ViewControllerr.textFieldDidChange(_:)), for: UIControl.Event.editingChanged)

I tried this, but don't quite understand the #selector input. Does it want my UIViewController? or my UIAlertController I tried both but got the same error message:

Value of type 'UIViewController' has no member 'textFieldDidChange'

Same with UIAlertController.

I also tried setting my textField to delegate to access functions of that class:

textField.delegate = self as? UITextFieldDelegate

But I guess this isn't the correct approach as I still couldn't access any functions except by doing:

textField.delegate?.textFieldDidBeginEditing?(textField)

But that didn't give me anything either.

I also tried adding an extension like this:

extension UITextFieldDelegate {
    func textFieldDidBeginEditing(_ textField: UITextField) {
        print("🦋EDITING")
}// became first responder

    func textFieldDidEndEditing(_ textField: UITextField) {
        print("🦋EDITING")
    }
}

But for some reason I can't access them through textView

If I extend the class like this:

extension PickNumberViewController: UITextFieldDelegate {...}

I get the same error message

Value of type 'UITextField' has no member 'textFieldDel...'

which makes no sense since I set textField to UITextFieldDelegate not UITextField.

Let me know if you would like to see my code as well.

Answer 1

You can try to get a reference to it with self.textF = alert.textFields?[0]

class ViewController: UIViewController {

    var textF:UITextField!

    override func viewDidLoad() {
        super.viewDidLoad()
        // Do any additional setup after loading the view.

        DispatchQueue.main.asyncAfter(deadline: .now() + 2) {

            //1. Create the alert controller.
            let alert = UIAlertController(title: "Some Title", message: "Enter a text", preferredStyle: .alert)
            alert.addTextField { (textField) in
                textField.text = "Some default text"
            }
             let tex = alert.addAction(UIAlertAction(title: "OK", style: .default, handler: { [weak alert] (_) in

            })) 
            // 4. Present the alert.
            self.present(alert, animated: true, completion: nil)

            self.textF =  alert.textFields?[0]

            self.textF.addTarget(self, action: #selector(self.textFieldDidChange), for: UIControl.Event.editingChanged)

        }


    }

    @objc func textFieldDidChange() {
        print(textF.text)
    }

}