How do I check when a UITextField changes?

Question

I am trying to check when a text field changes, equivalent too the function used for textView - textViewDidChange so far I have done this:

  func textFieldDidBeginEditing(textField: UITextField) {
        if self.status.text == "" && self.username.text == "" {
            self.topRightButton.enabled = false
        } else {   
            self.topRightButton.enabled = true
        }
    }

Which kind of works, but the topRightButton is enabled as soon as the text field is pressed on, I want it to be enabled only when text is actually typed in?

Answer 1

The way I've handled it so far : in UITextViewDelegate

func textField(textField: UITextField, shouldChangeCharactersInRange range: NSRange, replacementString string: String) -> Bool
{
    // text hasn't changed yet, you have to compute the text AFTER the edit yourself
    let updatedString = (textField.text as NSString?)?.stringByReplacingCharactersInRange(range, withString: string)

    // do whatever you need with this updated string (your code)


    // always return true so that changes propagate
    return true
}

Swift4 version

func textField(_ textField: UITextField, shouldChangeCharactersIn range: NSRange, replacementString string: String) -> Bool {
    let updatedString = (textField.text as NSString?)?.replacingCharacters(in: range, with: string)
    return true
}

Answer 2

Swift 4

Conform to UITextFieldDelegate.

func textField(_ textField: UITextField, shouldChangeCharactersIn range: NSRange, replacementString string: String) -> Bool {
    // figure out what the new string will be after the pending edit
    let updatedString = (textField.text as NSString?)?.replacingCharacters(in: range, with: string)

    // Do whatever you want here


    // Return true so that the change happens
    return true
}

Answer 3

Swift 3.0

textField.addTarget(self, action: #selector(textFieldDidChange(textField:)), for: .editingChanged)

and handle method:

func textFieldDidChange(textField: UITextField) { 

}

Swift 4.0

textField.addTarget(self, action: #selector(ViewController.textFieldDidChange(_:)),
                          for: UIControlEvents.editingChanged)

and handle method:

@objc func textFieldDidChange(_ textField: UITextField) {

}

Answer 4

Swift 3

 textField.addTarget(self, action: #selector(ViewController.textFieldDidChange(sender:)), for: UIControlEvents.editingChanged)

Answer 5

This is how you can add a textField text change listener using Swift 3:

Declare your class as UITextFieldDelegate

override func viewDidLoad() {
    super.viewDidLoad()

    textField.delegate = self

    textField.addTarget(self, action: #selector(UITextFieldDelegate.textFieldShouldEndEditing(_:)), for: UIControlEvents.editingChanged)
}

Then just traditionally add a textFieldShouldEndEditing function:

func textFieldShouldEndEditing(_ textField: UITextField) -> Bool { // do stuff
        return true 
}

Answer 6

You can use this delegate method from UITextFieldDelegate. It fires with every character change.

(Objective C) textField:shouldChangeCharactersInRange:replacementString:
(Swift) textField(_:shouldChangeCharactersInRange:replacementString:)

However THIS ONLY FIRES BEFORE a change is made (indeed, a change is only made if you do return true from here).