title: What effects does iOS add to UIBarButtonItem images?
body: <p>What effects does iOS add to <code>UIBarButtonItem</code> images? I want to put three of my "buttons" in a <code>UISegmentControl</code> segment to visually group them. However, <code>UISegmentControl</code> does not add the same effects that <code>UIBarButtonItem</code> does.</p>
  
  <p>There seems to be a black shadow just above the image in the <code>UIBarButtonItem</code>, but I haven't been able to match it through experimentation.</p>
  
  <p>I don't mind doing this in code or in a graphic editor, though I'd prefer code. :)</p>
  
  <p>Apple's docs say this, which I assume is the same basic approach:</p>
  
  <blockquote>
    <p>Toolbar images that represent normal and highlighted states of an item derive from the image you set using the inherited image property from the UIBarItem class. For example, the image is converted to white and then bevelled by adding a shadow for the normal state.</p>
  </blockquote>
  
  <p>My main concern is matching the shadow; the base colour is not black, and I don't know the opacity.</p>