title: Implicit declaration of function glGenFramebuffers
body: <p>Just getting started with Xcode and Open GL and I am getting 
  "Implicit declaration of function glGenFramebuffers" in my GL View class. I am importing </p>
  
  <pre><code>#import &lt;UIKit/UIKit.h&gt;
  #import &lt;QuartzCore/QuartzCore.h&gt;
  #import &lt;OpenGLES/ES1/gl.h&gt;
  </code></pre>
  
  <p>And I also tried with </p>
  
  <pre><code>#import &lt;OpenGLES/EAGL.h&gt;
  #import &lt;OpenGLES/ES1/gl.h&gt;
  #import &lt;OpenGLES/ES1/glext.h&gt;
  </code></pre>
  
  <p>and make clean all targets but the warning stays! What does it mean? What do I have to import for it to go away? </p>