Retina display core graphics font quality

Trying to understand why am I getting low quality drawing with CGContextShowTextAtPoint? See attached image:

The letter "W" is drawn using CGContextShowTextAtPoint on a CALayer and looks very pixelized. The button next to it is a standard button a开发者_如何学Pythonnd looks high res as expected. I would like to get the text drawing to be hi-res.

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By default, your CALayer is not rendering its Quartz content at the higher resolution of the Retina display screen. You can enable this using code like the following:

if ([layer respondsToSelector:@selector(setContentsScale:)])
{
    layer.contentsScale = [[UIScreen mainScreen] scale];
}

This will affect not just text rendering, but all of your Quartz drawing within CALayers, so you'll need to do this for all of your layers with custom Quartz content.

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Does using CGContextScaleCTM deliver any results for you? When working with a graphics context, something like this:

CGFloat scale = [[UIScreen mainScreen] scale];
CGContextRef context = UIGraphicsGetCurrentContext();
CGContextScaleCTM(context, scale, scale);

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Swift version:

textLayer.contentsScale = UIScreen.mainScreen().scale

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A group of functions controls how Core Graphics renders fonts:

• CGContextSetAllowsAntialiasing
• CGContextSetAllowsFontSmoothing
• CGContextSetAllowsFontSubpixelPositioning
• CGContextSetAllowsFontSubpixelQuantization