title: shadow under custom uiview
body: <p>I'm trying to add a shadow under my custom view, I have the following code:</p>
  
  <pre><code>CGContextSaveGState(context);
  CGContextSetShadow(context, CGSizeMake(0, 2), 3.0);
  CGRect shadowRect = CGRectMake(self.bounds.origin.x,
                                 self.bounds.origin.y + self.bounds.size.height,
                                 self.bounds.size.width,
                                 3.0);
  CGContextFillRect(context, shadowRect);
  CGContextRestoreGState(context);
  </code></pre>
  
  <p>But the shadow isn't visible.</p>