title: What is the best way to determine if a string contains a character from a set in Swift
body: <p>I need to determine if a string contains any of the characters from a custom set that I have defined.</p>
  <p>I see from <a href="https://stackoverflow.com/questions/24034043/how-do-i-check-if-a-string-contains-another-string-in-swift">this</a> post that you can use rangeOfString to determine if a string contains another string. This, of course, also works for characters if you test each character one at a time.</p>
  <p>I'm wondering what the best way to do this is.</p>