textField форматирование номера телефона (UITextField for Phone Number format) 2 вариант - Swift 5

extension NewTaskTableViewController : UITextFieldDelegate {
func formattedNumber(number: String) -> String {
let cleanPhoneNumber = number.components(separatedBy: CharacterSet.decimalDigits.inverted).joined()
let mask = "+X (XXX) XXX-XXXX"

var result = ""
var index = cleanPhoneNumber.startIndex
for ch in mask where index < cleanPhoneNumber.endIndex {
if ch == "X" {
result.append(cleanPhoneNumber[index])
index = cleanPhoneNumber.index(after: index)
} else {
result.append(ch)
}
}
return result
}


func textField(_ textField: UITextField, shouldChangeCharactersIn range: NSRange, replacementString string: String) -> Bool
{
guard let text = phoneNumberTextField.text else { return false }
let newString = (text as NSString).replacingCharacters(in: range, with: string)
textField.text = formattedNumber(number: newString)
return false
}
}

Masks
"" => ""
"0" => "+0"
"412" => "+4 (12"
"12345678901" => "+1 (234) 567-8901"