title: How to render to offscreen bitmap then blit to screen using Core Graphics
body: <p>I would like to render to an offscreen bitmap (or array of RGBA values) and then blit those to a <code>UIView</code> during in the view's <code>drawRect</code> function. I would prefer to do full 32-bit rendering (including alpha channel), but would also be content with 24-bit rendering.</p>
  
  <p>Would anyone mind pointing me in the right direction with some code snippets or relevant APIs?</p>
  
  <p>Also, I know exactly how to do this using OpenGL - I would just prefer to do this work in Core Graphics itself.</p>