title: stringByReplacingCharactersInRange does not work?
body: <p>I am attempting to replace a character with another one. For some reason stringByReplacingCharactersInRange does not work. I have not found a simple explanation on how to resolve this issue.</p>
  
  <pre><code>var binaryColor: String = "000"
  (binaryColor as NSString).stringByReplacingCharactersInRange(NSMakeRange(0, 1), withString: "1")
  println("This is binaryColor0: \(binaryColor)")
  </code></pre>
  
  <p>The result is 000 and not 100.
  Thanks for any help!</p>