title: Method available in project but not in playground
body: <p>I'm new to Swift - using Swift 3, Xcode 8.0 beta 6, Mac OS X 10.11.6.  The following line works in my project (it's a simple test case to see if the 'contains' method is working):</p>
  
  <pre><code>if ("hello John".contains("John")){}
  </code></pre>
  
  <p>It works fine in my project, but when I cut and paste it into a playground project, it gives an error: </p>
  
  <blockquote>
    <p>"Value of type 'String' has no member 'contains'".</p>
  </blockquote>
  
  <p>My question is, apart from why this error is being thrown, are there different frameworks/functions/methods etc. being used in playground projects from normal projects?
  Thanks for your help.
  Squire.</p>