title: 'advancedBy' is unavailable in Xcode 8
body: <p>Currently, I've been using XCode 8 and on the line</p>
  
  <pre><code>let range = key.startIndex...key.startIndex.advancedBy(0)
  </code></pre>
  
  <p>I get the error:</p>
  
  <blockquote>
    <p>error: 'advancedBy' is unavailable: To advance an index by n steps call 'index(_:offsetBy:)' on the CharacterView instance that produced the index.</p>
  </blockquote>
  
  <p>How can I fix this?</p>
  
  <p>A screenshot of the error is below:</p>
  
  <p><a href="https://i.stack.imgur.com/FQvd5.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/FQvd5.png" alt="advancedBy is unavailable"></a></p>