title: How do I define preprocessor macros in Xcode 4?
body: <p>I have two targets set up for my app (a lite version and a pro version) and I want to integrate some subtle differences in the code for each of them (e.g. the pro version will not show any iAd banners).</p>
  
  <p>I have been looking around and I see the easiest way to do this is through the use of preprocessor macros. The issue I'm facing is how to set them up in Xcode 4. I want to set up a macro called 'PRO_VERSION' in one target &amp; 'LITE_VERSION' in the other.</p>
  
  <p>Below is an example of how I intend to use them:</p>
  
  <pre><code>#ifdef PRO_VERSION
      // Hide ad banners
  #else
      // Show ad banners
  #endif
  </code></pre>