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What are layer objects?

· One min read
Ace the iOS Interview
Aryaman Sharda
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Main Source: đź”— Ace the iOS Interview

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TL/DR

Every UIView has a CALayer property which is responsible for the actual rendering of visual content and animations.

That’s why we’ll often write code like this:

layer.shadowOpacity = 0.3
layer.shadowRadius = 2
layer.shadowOffset = CGSize(width: 0 , height: 2 )
layer.borderWidth = 0

We’re giving instructions directly to the rendering component of the UIView.

There is an important distinction between the UIView and the CALayer. The UIView takes care of its own layout and placement, but it is the CALayer that is responsible for rendering its actual contents, including borders, shadows, corner radius, complex animations, and other visual effects.