// check the name is between 4 and 16 characters
if !(4...16 ~= name.characters.count) {
    return false
}

// check that name doesn't contain whitespace or newline characters
let range = name.rangeOfCharacterFromSet(.whitespaceAndNewlineCharacterSet())
  if let range = range where range.startIndex != range.endIndex {
  return false
}