UITextfield keyboard with only alphabet, no numbers, no caps, no spacebar?

Question

I want the keyboard for the UITextfield to only have a-z, no numbers, no special characters (!@$!@$@!#), and no caps. Basicly I am going for a keyboard with only the alphabet.

Answer 1

all the answers is working when user is not copy and paste in textfield for copy and paste to work use blow code

func textField(_ textField: UITextField, shouldChangeCharactersIn range: NSRange, replacementString string: String) -> Bool {

    let text = (textField.text! as NSString).replacingCharacters(in: range, with: string)
    let Regex = "[a-z A-Z ]+"
    let predicate = NSPredicate.init(format: "SELF MATCHES %@", Regex)
    if predicate.evaluate(with: text) || string == ""
    {
        return true
    }
    else
    {
        return false
    }

}

Answer 2

Swift 3 with spaces

func textField(_ textField: UITextField, shouldChangeCharactersIn range: NSRange, replacementString string: String) -> Bool {
    if string == " " { return true }
    if let _ = string.rangeOfCharacter(from: CharacterSet.letters){
        return true
    }
    return false
}