title: Use of undeclared identifier 'arc4random' after Xcode 4.6 update
body: <p>I just ran the Xcode 4.6 update, and now my project will not compile. I had to fix several C++ errors, but one of my C++ files is still getting this one <code>Use of undeclared identifier 'arc4random'</code>.</p>
  
  <p>Note that <code>arc4random()</code> works elsewhere in the project just fine. (Even in other C++ files!)</p>
  
  <p>I've tried changing it to <code>arc4random_uniform(1)</code>, but that doesn't help.</p>
  
  <p>Thanks for reading.</p>