title: Background image for CATiledLayer
body: <p>As you might know, <code>CATiledLayer</code> is used to display large images by showing tiled images at scale suitable for view size.</p>
  
  <p>I have <code>CATiledLayer</code> working similar to example which could be found under iOS documentation and I calculate at which row and column <code>drawRect:(CGRect)</code> rect is trying to draw its content. </p>
  
  <p>When view appears for the first time it starts drawing tile by tile on blank view with nothing behind that view/layer. I'm trying to put low resolution image at first to fill up the layer and then start drawing tiled view.</p>
  
  <p>Just like when you're moving through PDF pages, each page is at first represented with a very poor image but it's enough to see content layout and when you stop at certain page this page becomes more clearer.</p>
  
  <p>I know I can add sublayers on top of catiledlayer but I'm not able to put any layer behind catiledlayer because this is a masterlayer. I also believe that it's important to load image for background on the same layer so that could be proper scaled.</p>
  
  <p>Has anyone an idea how to achieve this?</p>