title: UIView animation vs CALayers
body: <p>I'm struggling with conceptualizing animations with a <strong>CALayer</strong> as opposed to <strong>UIView's</strong> own animation methods. Throw "<strong>Core Animation</strong>" into this and, well, maybe someone can articulate these concepts from a high level so I can better visualize what's happening and why I'd want to migrate UIView animations (which I'm quite familiar with now) to CALayer animations on the iPhone. Every view in Cocoa-Touch automatically gets a layer. And, it seems, you can animate one <em>and/or the other?!?</em> Even mix them together?!? But why? Where's the line? What's the pro/con to each?</p>
  
  <p>The Core Animation Programming Guide immediately jumps into Layer &amp; Timing Classes and I think need to take a step back and understand why these varied pieces exist and how relate to each other.</p>