为什么添加子层会与子视图重叠? [英] Why adding sublayer overlaps subviews?

问题描述

例如，我有一个带有UILabel的视图作为子视图.如果在某个时候将具有某种背景颜色的子层添加到该视图的层，则该标签将消失.有人可以解释这种行为吗?

For example I have a view with UILabel as subview. If at some time I add sublayer with some background color to this view's layer, then this label will disappear. Can someone explain this behavior?

推荐答案

将UILabel添加为视图的子视图时，它会将UILabel的图层添加为视图层的子层.因此，当您在视图的图层中添加另一个子图层时，它将位于UILabel图层的顶部.

When you add your UILabel as a subview of your view it is adding your UILabel's layer as a sublayer of your view's layer. So when you add another sublayer to your view's layer it will be on top of your UILabel's layer.

您可以在添加UILabel之前添加背景层，也可以执行以下操作:

You can either add your background layer before you add the UILabel or do:

快速

view.layer.insertSublayer(backgroundLayer, below: yourLabel.layer)

目标C

[view.layer insertSublayer:backgroundLayer below:yourLabel.layer]

它应该将背景放在标签后面.

and it should put the background behind the label.

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