title: CGImage (or UIImage) from a CALayer
body: <p>I have created a <code>CALayer</code>
   (I added several shapes to the layer, but ultimately, I have a single CALayer), and I am having a LOT of trouble adding it to a CGImage.  I have found some references to <code>[CALayer renderInContext:ctx]</code>, but I am not sure how to implement it.</p>
  
  <p>Has anyone done this before?</p>