How shouldChangeCharactersInRange works in Swift?

Question

I\'m using shouldChangeCharactersInRange as a way of using on-the-fly type search.

However I\'m having a problem, shouldChangeCharactersInRange get

Answer 1

stringByReplacingCharactersInRange return a new string, so how about:

func textField(textField: UITextField!, shouldChangeCharactersInRange range: NSRange, replacementString string: String!) -> Bool {
    if let text = textField.text as NSString? {
        let txtAfterUpdate = text.replacingCharacters(in: range, with: string)
        self.callMyMethod(txtAfterUpdate)
    }
    return true
}