Is it possible to get the deleted/removed character on backspace in unity?

Question

I want to know the deleted character on backspace in unity. I need to check the particular end character of the string.

e.g. abcd<quad material =0 size => 89 >

If the string ends with '>' - checks for the condition, and will do some operations based on this.

This check is happening on backspace but, on pressing backspace, the '>' gets deleted and this condition remains false always. So, is there any way I can know the deleted character on backspace.

Answer 1

Assuming you are talking about an UI.InputField you could probably use onValidateInput and check if the input was a backspace char (\b).

Maybe something like e.g.

[SerializeField] private InputField _inputField;

private void Awake ()
{
    if(!_inputField) _inputField = GetComponent<InputField>();

    _inputField.onValidateInput += CheckInput;
}

private void OnDestroy()
{
    _inputField.onValidateInput -= CheckInput;
}

private char CheckInput(char charToValidate)
{
    if (charToValidate == '\b')
    {
        var lastChar = _inputField.text[_inputField.text.Length - 1];
        //ToDo Do something with lastChar         
    }

    return charToValidate;
}

onValidateInput as far as I remember is executed before the character is actually added to the input, thus before e.g. onValueChanged is called.

---

As alternative you could of course also simply store the last value of the field and check it onValueChanged like e.g.

[SerializeField] private InputField _inputField;

private string _lastValue;

private void Awake ()
{
    if(!_inputField) _inputField = GetComponent<InputField>();

    _inputField.onValueChanged += CheckInput;
    _lastValue = _inputField.text;
}

private void OnDestroy()
{
    _inputField.onValueChanged -= CheckInput;
}

private char CheckInput()
{
    var lastChar = _lastValue[_lastValue.Length - 1];

    //ToDo Do something with lastChar  
   
    
    // Update the last value
    _lastValue = _inputField.text;
}