title: Create the indented look found in UINavigationBarButton - programmatically
body: <p>I'm trying to programmatically recreate the indented button look that can be seen on a UINavigationBarButton.  Not the shiny two tone look or the gradient, just the perimeter shading:</p>
  
  <p><img src="https://i.stack.imgur.com/OcKPI.png" alt="enter image description here"></p>
  
  <p>It looks like an internal dark shadowing around the entire view perimeter, slightly darker at the top?  And then an external highlighting shadow around the lower view perimeter. </p>
  
  <p>I've played a bit with Core Graphics, and experimented with QuartzCore and shadowing with view.layer.shadowRadius and .shadowOffset, but can't even get the lower highlighting to look right.  I'm also not sure where to start to achieve both a dark shadowing with internal offset and a light shadowing with external offset.</p>