textfield.becomeFirstResponder isn't keeping text field focused in swift - ios

Question

I have a page where there is a UITextField that I add programmatically, I set the text type to number and add constraints and all that. Then I add a done button to the accessoryView of the text field and add a function to run when that done button is pressed. My problem is, when the page loads, I want the text field to be focused and the keyboard shown. I set the becomeFirstResponder on it, but when the page loads, the keyboard shows up for a split second then immediately disappears and the delegate methods are run.
I need to find a way to make the text field "active", "focused", whatever you want to call it when the page loads, and for the keyboard to be there and ready. I can't seem to find any help aside from call becomeFirstResponder on it, which only works for a split second.
Here is the code I am using to build the page and run everything, I simplified it to reduce clutter and read times, but if you need more info, please let me know and I will be happy to provide the full code...
class AgeViewController: UIViewController {
var selectedAge: Int = 0
var textInput: UITextField!
let settings = UserDefaults.standard
override func viewDidLoad() {
super.viewDidLoad()
createPage()
}
override func viewWillAppear(_ animated: Bool) {
textInput.becomeFirstResponder()
//I have tried this in both viewWillAppear and viewDidAppear
}
func createPage() {
textInput = UITextField()
textInput.font = .systemFont(ofSize: 50)
textInput.placeholder = "35"
textInput.borderStyle = .none
textInput.keyboardType = .numberPad
textInput.returnKey = .done
textInput.textAlignment = .right
addDoneButton()
textInput.delegate = self
view.addSubView(textInput)
//create a label and add it to the page
}
private fun addDoneButton() {
let doneToolbar: UIToolbar = UIToolbar(frame: CGRect(x: 0, y: 0, width: UIScreen.main.bounds.width, height: 50)
doneToolbar.barStyle = .default
let flexSpace = UIBarButtonItem(barButtonSystemItem: .flexibleSpace, target: nil, action: nil)
let done: UIBarButtonItem = UIBarButtonItem(title: "Done", style: .done, target: self, action: #selector(doneTapped))
let items = [flexSpace, done]
doneToolbar.sizeToFit()
textInput.inputAccessoryView = doneToolbar
}
#objc func doneTapped() {
textInput.resignFirstResponder()
}
}
extension AgeViewController: UITextFieldDelegate {
func textFieldDidBeginEditing(_ textField: UITextField) {
textField.textColor = UIColor(named: "text")!
}
func textFieldDidEndEditing(_ textField: UITextField, reason: UITextField.DidEndEditingReason) {
if textField.text != nil {
selectedAge = Int(textField.text!) ?? 35
settings.set(selectedAge, forKey: Strings.age)
} else {
textField.textColor = UIColor(named: "grayText")!
}
}
Like I said, the page loads, the keyboard shows up for a split second, then goes away and the delegate methods are called for didEndEditing. I don't understand why it isn't staying focused, I am calling becomeFirstResponder. I have tried calling textInput.becomeFirstResponder() in 3 different places, all with the same result. The first was right after I add the subview to the view, then I tried in viewDidAppear and finally in viewWillAppear, all have the same result, shows up for a split second, then goes away. Sorry for the long post, thank you for any help, I really appreciate it.