We use a custom font face and custom font sizes in our application. When running the application on an iPhone 6 (haven't tried 6+ yet but I assume it's the same) all fonts look blurry. We also have an internal tool that uses the system font and it looks blurry as well.
Why is that and what is the right approach to get them to render as crisp as they do on an iPhone 5?
Perhaps your labels or drawing points aren't on an exact pixel, but instead on a fractional pixel. To prevent such situations use methods like ceilf(), floorf() and CGRectIntegral().
来源：https://stackoverflow.com/questions/26288350/how-to-fix-blurred-text-on-an-iphone-6