title: unichar and NSString - how interchangeable are these?
body: <p>There is an <code>NSString</code> method <code>-characterAtIndex:</code> which returns an unichar.</p>
  
  <blockquote>
    <ul>
    <li>(unichar)characterAtIndex:(NSUInteger)index</li>
    </ul>
  </blockquote>
  
  <p>I wonder if this unichar, which obviously is not an <code>NSString</code>, can be converted into an <code>NSString</code> or feeded to an <code>NSString</code> for comparing purposes?</p>
  
  <p>And: Does an <code>NSString</code> internally just consist of an array of unichar items?</p>