How to restrict certain characters in UITextField in Swift?

Question

I am creating a trivia application that asks for a username on start up. I\'d like to make it impossible to use characters such as #$@!^& etc (also including \"space\").

Answer 1

Swift : 3 and a different approach:

Add a target function for the text field change in your viewDidLoad:

    override func viewDidLoad() {
    super.viewDidLoad()
textField.addTarget(self, action: #selector(ViewController.textFieldDidChange(textField:)), for: UIControlEvents.editingChanged)
 }

in the target function, simply detect the entered char and replace it with blank. I have tested it and it prevents the user from entering any non desirable characters in the text field.

 func textFieldDidChange(textField: UITextField) {

    if let textInField = textField.text{
        if let lastChar = textInField.characters.last{

            //here include more characters which you don't want user to put in the text field
            if(lastChar == "*")
            {

                textField.text  = textInField.substring(to: textInField.index(before: textInField.endIndex))

            }
        }
    }

}