title: Custom drawing with CATiledLayer creates artifacts
body: <p>I've got a simple UIView class that draws some text in it's drawRect routine:</p>
  
  <pre><code>[mString drawInRect:theFrameRect  withFont:theFont];
  </code></pre>
  
  <p>That looks OK at regular resolution, but when zoomed, it's fuzzy:
  [image removed, not enough posts]</p>
  
  <p>So, I added some tiling:</p>
  
  <pre><code>CATiledLayer *theLayer = (CATiledLayer *) self.layer;
  theLayer.levelsOfDetailBias = 8;
  theLayer.levelsOfDetail = 8;
  theLayer.tileSize = CGSizeMake(1024,1024);
  </code></pre>
  
  <p>(plus the requisite layerClass routine)</p>
  
  <p>but now the text will draw twice, when zoomed, when the size of the frame is larger than the size of tile:
  [image removed, not enough posts]</p>
  
  <p>I'm not clear as to the solution for this. Drawing the text is an atomic operation. I could figure out how to calculate what portion of the text to draw based on the rect that's passed in...but is that really the way to go? Older code examples use drawLayer, but that seems to have been obviated by iOS 5, and is clearly more cumbersome than a straight drawRect call. </p>