title: Function that expects an UnsafeMutablePointer<Type>!
body: <p>I'm trying to render an offscreen image with OpenGL following the <a href="https://developer.apple.com/library/content/documentation/GraphicsImaging/Conceptual/OpenGL-MacProgGuide/opengl_offscreen/opengl_offscreen.html#//apple_ref/doc/uid/TP40001987-CH403-SW16" rel="nofollow noreferrer">Apple documentation</a> (written in Objective-C). I've created a simple Cocoa CLI project and added this code as a primer within the main.swift file but I can't manage to compile it:</p>
  
  <pre><code>import Foundation
  import AGL
  
  var framebuffer: GLuint
  
  glGenFramebuffersEXT(1, &amp;framebuffer)
  </code></pre>
  
  <p>With this code I get the following message from the compiler: <code>Address of variable 'framebuffer' taken before it is initialized</code>.</p>
  
  <p>The signature of the OpenGL function is <code>func glGenFramebuffersEXT(_ n: GLsizei, _ framebuffers: UnsafeMutablePointer&lt;GLuint&gt;!)</code>.</p>
  
  <p>When trying with <code>var framebuffer: GLuint = 0</code> the program simply crashes.</p>
  
  <p>How should I initialize the <code>framebuffer</code>variable to make this work?</p>