ios - self.button.layer.backgroundColor 和 self.button.backgroundColor 有什么区别？

Question

这两行 Swift 代码在功能上有区别吗？

self.button.layer.backgroundColor = UIColor.whiteColor().CGColor

和

self.button.backgroundColor = UIColor.whiteColor()

?

Answer 1

根据 John Blanco's blog :

Every UIView comes packaged with a CALayer knows as the “backing layer” or “underlying layer.” Many of the methods you call on UIView simply delegate to the layer. When you change a view’s frame, it’s simply changing the layer’s frame. If you change the alpha, it changes the layer’s alpha…and so on with background colors, transformations and more. And while you can maintain a hierarchy of UIViews each representing parents and children of one another, you can do the same with CALayer