title: How to remove duplicate characters from a string in Swift
body: <p>ruby has the function string.squeeze, but I can't seem to find a swift equivalent. </p>
  
  <p>For example I want to turn bookkeeper -> bokepr</p>
  
  <p>Is my only option to create a set of the characters and then pull the characters from the set back to a string? </p>
  
  <p>Is there a better way to do this?</p>