title: Xcode complains about Unused functions that are used
body: <p>I have a "MyConstants.h" file that is imported by several classes.</p>
  
  <p>Inside that file I have things like:</p>
  
  <pre><code>static BOOL isIndexValid(NSInteger index) {
    return ((index &gt;=0) &amp;&amp; (index &lt; 200));
  }
  </code></pre>
  
  <p>This function is extensively used by the classes importing <code>MyConstants.h</code>. Even so, Xcode complains that this function and others are not used.</p>
  
  <p>Why?</p>