为什么CALayer的visibleRect方法为我的UIImageView提供了相同的宽度，即使我将它移出屏幕一半？

I get the visibleRect from an UIImageView inside a method, that is called several times to move that view to the right. As soon as it goes partly out of the screen, I expect that the visibleRect becomes smaller. But it does not.I get the visibleRect from an UIImageView insid