Allow only alphanumeric characters for a UITextField

Question

How would I go about allowing inputting only alphanumeric characters in an iOS UITextField?

Answer 1

The RegEx way in Swift:

func textField(_ textField: UITextField, shouldChangeCharactersIn range: NSRange, replacementString string: String) -> Bool {
     if string.isEmpty {
         return true
     }
     let alphaNumericRegEx = "[a-zA-Z0-9]"
     let predicate = NSPredicate(format:"SELF MATCHES %@", alphaNumericRegEx)
     return predicate.evaluate(with: string)
}