I believe you need to set the scale of the layer to the scale of the device. 
Here is how we do it where appContentScaleFactor is a global variable we store 
the scale from at startup:

        if ([[UIScreen mainScreen] respondsToSelector: @selector(scale)])
                appContentScaleFactor = [[UIScreen mainScreen] scale];


                if ([mainLayer respondsToSelector: 
@selector(setContentsScale:)])
                        mainLayer.contentsScale = appContentScaleFactor;


On Aug 28, 2010, at 3:22 PM, Matt Neuburg wrote:

> In my UIView's drawRect: I derive a CGLayer from the current context, draw
> into it, and then draw the layer into the context (the view). This still
> works on iPhone with a Retina display, but the drawing is blocky. You can
> see the problem perfectly with Apple's own example code (DrawFlag) in the
> CGLayer Drawing page of the Quartz 2D Programming Guide - the stars in the
> flag are blocky.
> 
> I can work around the problem for a double-resolution screen by creating a
> CGLayer twice the size I need, applying a doubling scale transform, drawing
> as before into the CGLayer, and then drawing the CGLayer into my view's
> context scaled back down again.
> 
> But I feel I shouldn't have to do this. Given that the documentation claims
> that "a CGLayer has all the characteristics of the graphics context [from
> which it is derived] - its resolution, colorspace, and graphics state
> settings," might we call this a bug?
> 
> m.
> 
> -- 
> matt neuburg, phd = m...@tidbits.com, http://www.tidbits.com/matt/
> pantes anthropoi tou eidenai oregontai phusei
> Among the 2007 MacTech Top 25, http://tinyurl.com/2rh4pf
> AppleScript: the Definitive Guide, 2nd edition
> http://www.tidbits.com/matt/default.html#applescriptthings
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> http://tinyurl.com/kufyy8
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> 
> 
> 
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