title: CoreGraphics code isn't making a hollow shape, as expected
body: <p>This is the code I have:</p>
  
  <pre><code>CGContextRef context = UIGraphicsGetCurrentContext();
      CGColorRef redColor = [UIColor colorWithRed:1.0 green:0.0 blue:0.0 alpha:1.0].CGColor;
  
  CGRect rectangle = CGRectMake(100, 100, 100, 100);
      CGRect inside = CGRectMake(120, 120, 60, 60);
  
  
  
  CGContextSetFillColorWithColor(context, redColor);
  CGContextSetBlendMode(context, kCGBlendModeNormal);
  CGContextFillRect(context, rectangle);
  CGContextSaveGState(context);
  
  CGContextSetBlendMode(context, kCGBlendModeSourceOut);
  CGContextFillRect(context, inside);
  CGContextRestoreGState(context);
  </code></pre>
  
  <p>I'm trying to make the inside shape hollow, but instead it's giving me a red square (as expecetd) with a black square in the middle, when the UIView in the background is white.</p>
  
  <p>Any ideas on how to make the shape transparent here?</p>