Where do I call my function so it successfully updates my UI? - swift

Question

I have written the following function to ensure my user fills in a textField before being able to continue.
func validateFields() -> String {
if textfield.text?.trimmingCharacters(in: .whitespacesAndNewlines) == "" {
return "Please fill in textField"
}
return "A-OK."
}
func updateUI() {
let verdict = validateFields()
if verdict == "A-OK." {
self.buttonOne.alpha = 1
}
}
override func viewDidLoad() {
super.viewDidLoad()
updateUI()
}
However, once the textField has been filled in, the above code fails to update the UI. I know I am missing out on something trivial here, I just cannot wrap my head around what. I'd really appreciate the help.

Answer 1

Use text textFieldDidEndEditing, textFieldDidBeginEditing, textFieldShouldReturn, etc. according to your requirement.
But I think delegate "textFieldShouldReturn" works fine with your requirement.
You just need to add you function updateUI() in this delegate.

Answer 2

That's easy you can create an outlet of your text fields and give its
delegate to self in viewDidLoad() method
#IBOutlet var txtfld: UITextField!
override func viewDidLoad() {
super.viewDidLoad()
txtfld.delegate = self
}
// UITextField Delegates
func textFieldDidBeginEditing(_ textField: UITextField) {
print("TextField did begin editing method called")
}
func textFieldDidEndEditing(_ textField: UITextField) {
print("TextField did end editing method called")
}
func textFieldShouldBeginEditing(_ textField: UITextField) -> Bool {
print("TextField should begin editing method called")
return true;
}
func textFieldShouldClear(_ textField: UITextField) -> Bool {
print("TextField should clear method called")
return true;
}
func textFieldShouldEndEditing(_ textField: UITextField) -> Bool {
print("TextField should end editing method called")
return true;
}
func textField(_ textField: UITextField, shouldChangeCharactersIn range: NSRange, replacementString string: String) -> Bool {
print("While entering the characters this method gets called")
return true;
}
func textFieldShouldReturn(_ textField: UITextField) -> Bool {
print("TextField should return method called")
textField.resignFirstResponder();
return true;
}
}
I suggest for calling your method you should use your updateUI()
function in textFieldShouldReturn(_ textField: UITextField) this
method.

Answer 3

I suppose you can easily bind you text view to a local property and observer changes on that property. And when everything is valid, you can enable your buttonOne and use the value of that property in future computations.
var myTextFieldData: String {
didSet {
updateUI()
}
}
Also, keep in mind that you'll also have to implement the UITextField delegate in order to bind your textField with myTextFieldData:
textField.delegate = self
func textField(_ textField: UITextField, shouldChangeCharactersIn range: NSRange, replacementString string: String) -> Bool {
myTextFieldData = string
return true
}