How to remove all chars except those in CharacterSet in Swift

Question

I am trying to trim a phone number and using the following code but it does not trim whitespace or the '-'. I need to erase all chars except those in the character set given

 func trimmedNumber(s : String)->String
 {
    let characterSet = NSCharacterSet(charactersInString: "+*#0123456789")
   let trimmedString =  s.stringByTrimmingCharactersInSet(characterSet.invertedSet)
    return trimmedString
}

Answer 1

Swift 3/4:

let set = CharacterSet(charactersIn: "+*#0123456789")
let stripped = s.components(separatedBy: set.inverted).joined()

Answer 2

func trimmedNumber(s : String) -> String {
  let characterSet = Set("+*#0123456789".characters)
  return String(s.characters.lazy.filter(characterSet.contains))
}

Or in Swift 1:

func trimmedNumber(s : String) -> String {
  let characterSet = Set("+*#0123456789")
  return String(lazy(s).filter { characterSet.contains($0) })
}