Validate UITextField text letter by letter as it is entered - ios

Question

So I have a validation for my textfield, if the validation is true my button will be enabled and if the validation is false my button will be disable. The problem is the validation only runs after I click the done button in the keyboard.
I want the validation check letter by letter.
Here is my code:
func textFieldDidEndEditing(_ textField: UITextField) {
if (nomorTextField.text!.count >= 10) {
nextButton.isEnabled = true
nextButton.backgroundColor = #colorLiteral(red: 1, green: 0.4431372549, blue: 0.003921568627, alpha: 1)
if(nomorTextField.text!.count > 13) {
nextButton.isEnabled = false
nextButton.backgroundColor = #colorLiteral(red: 0.662745098, green: 0.662745098, blue: 0.662745098, alpha: 1)
}
else if emailTextFeild.text == "" {
nextButton.isEnabled = true
nextButton.backgroundColor = #colorLiteral(red: 1, green: 0.4431372549, blue: 0.003921568627, alpha: 1)
}
else if emailTextFeild.text?.isEmail == false {
nextButton.isEnabled = false
nextButton.backgroundColor = #colorLiteral(red: 0.662745098, green: 0.662745098, blue: 0.662745098, alpha: 1)
}
}
else {
nextButton.isEnabled = false
nextButton.backgroundColor = #colorLiteral(red: 0.662745098, green: 0.662745098, blue: 0.662745098, alpha: 1)
}
}

Answer 1

You can also connect it as an IBAction from storyboard (if you're using storyboards)
P.S. don't forget to change type to UITextField, and event to ValueChanged.

Answer 2

You should use a different delegate method -
textField(_:shouldChangeCharactersIn:replacementString:)
This method is called right before the characters are changed in the text field. You should always return true because in your case you are not looking to prevent text edits. However you do need to update the edited text field text with the new characters to make sure the count is correct.
func textField(_ textField: UITextField, shouldChangeCharactersIn range: NSRange, replacementString string: String) -> Bool {
// Casting String as NSString to be able to replace characters using NSRange easily.
guard let text = textField.text as NSString? else { return true }
// Get the length of the final text
let finalTextCount = text.replacingCharacters(in: range, with: string).count
// Setup the text count for the field depending on which one was edited
let nomorTextFieldCount = textField == nomorTextField ? finalTextCount :
nomorTextField.text!.count
if nomorTextFieldCount >= 10 {
nextButton.isEnabled = true
nextButton.backgroundColor = #colorLiteral(red: 1, green: 0.4431372549, blue: 0.003921568627, alpha: 1)
if nomorTextFieldCount > 13 {
nextButton.isEnabled = false
nextButton.backgroundColor = #colorLiteral(red: 0.662745098, green: 0.662745098, blue: 0.662745098, alpha: 1)
}else if emailTextFeild.text == "" {
nextButton.isEnabled = true
nextButton.backgroundColor = #colorLiteral(red: 1, green: 0.4431372549, blue: 0.003921568627, alpha: 1)
}else if emailTextFeild.text?.isEmail == false{
nextButton.isEnabled = false
nextButton.backgroundColor = #colorLiteral(red: 0.662745098, green: 0.662745098, blue: 0.662745098, alpha: 1)
}
}else{
nextButton.isEnabled = false
nextButton.backgroundColor = #colorLiteral(red: 0.662745098, green: 0.662745098, blue: 0.662745098, alpha: 1)
}
return true
}