Limit UITextField input to numbers in Swift

Question

How can I get limit the user\'s TextField input to numbers in Swift?

Answer 1

For anyone looking for a shorter answer, I've found this quite useful.

func textField(_ textField: UITextField, shouldChangeCharactersIn range: NSRange, replacementString string: String) -> Bool {
    // remove non-numerics and compare with original string
    return string == string.filter("0123456789".contains)
}

Works in XCode 10.1, Swift 4.2