I am working on an app where I am using CGContextShowTextAtPoint to display text to the screen. I want to also display Japanese characters, but CGContextS
For what it's worth, I spent a long time trying to get Japanese characters to work well in CoreGraphics, and didn't like where it left me.
In the end I switched to using UILabels to handle the text. All the CoreGraphics-like stuff I needed could be replicated using the transform & animation support, and in the end the resulting code was much simpler.
It may not be appropriate for your situation, but it's worth considering.