How can I remove or replace all punctuation characters from a String?

Question

I have a string composed of words, some of which contain punctuation, which I would like to remove, but I have been unable to figure out how to do this.

For example if I

Answer 1

Xcode 11.4 • Swift 5.2 or later

extension StringProtocol {
    var words: [SubSequence] {
        split(whereSeparator: \.isLetter.negation)
    }
}

---

extension Bool {
    var negation: Bool { !self }
}

---

let sentence = "Hello, this : is .. a  string?"
let words = sentence.words  // ["Hello", "this", "is", "a", "string"]