title: Cannot set depth buffer?
body: <p>In <a href="http://www.cocos2d-iphone.org/wiki/doku.php/prog_guide%3aeffects" rel="nofollow">some cocos2d-iphone documentation</a>, I was told to put this</p>
  
  <pre><code>// IMPORTANT: Call this function at the very beginning, before running your 1st scene
  // Create a depth buffer of 24 bits
  // These means that openGL z-order will be taken into account
  [[CCDirector sharedDirector] setDepthBufferFormat:kDepthBuffer16];
  </code></pre>
  
  <p>To allow some 3D effects in my game with actions. However, for some reason, neither <code>setDepthBufferFormat</code> nor <code>kDepthBuffer16</code> are recognized by XCode. Any ideas?</p>