How do I achieve a clearly rendered rotated UILabel?

问题

I am trying to display rotated text. The UILabel is added as a subview on a UIImageView. The UIImageView has a transform created via say CGAffineTransformMakeRotation(M_PI/4.0). The text of the UILabel renders fairly blurry cf. the title label (in the screenshot, the blue background 'What's ...').

Do you know how I can manage to make the rotated text render clearly?

I've already tried using an integral-based frame (which matters little since it'll be rotated), a non-clear background color, and setting the label to opaque=YES. Still blurry.

Thanks!

回答1:

The problem is that your label is rendered in half pixel either in the origin of the frame or the rotation. Check the frame origin after rotation, or try to rotate it by M_PI/4.1 (4.2, 4.3, 4.4, 4.5 - even test values like 4.05 4.15..) until it renders normally. Also check the frame of the UILabel in the UIImageView, could be added at half pixel origin for ex. {0.5, 0.5} or something..

来源：https://stackoverflow.com/questions/10492367/how-do-i-achieve-a-clearly-rendered-rotated-uilabel