title: How do you supress OpenGL messages in Xcode for iOS 12.0
body: <p>I'm using an old version of Cocos2d-iphone and need to come up with one last release before I completely reconfigure my app for Metal support.  Until then, I'm trying to work through all the deprecated issues besides the OpenGL stuff.  As it is, I have well over 400+ messages that say </p>
  
  <pre><code>"_____ is deprecated: first deprecated in iOS 12.0 - OpenGLES API deprecated. (Define GLES_SILENCE_DEPRECATION to silence these warnings)_
  </code></pre>
  
  <p>Where do I define this in my project?  I tried putting it in the top of my global.h header as well as a few other places, but I can't seem to get rid of it.</p>