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iosuikitcalayer

Meaning of backing store in CALayer

I was reading a ariticle and I got a question in this section of View Architecture Fundamentals.

Every view in UIKit is backed by a layer object (usually an instance of the CALayer class), which manages the backing store for the view and handles view-related animations.

What does backing store mean?

Is it just that root CALayer in UIView stacks a each layer in some area and that area is backing store?

or some area for caching(or backing-up) current UIView status?

and I'd like to know how the backing store works.

Thanks.

Solution

  • The layer is the basis of the render tree — what should be drawn on the screen to represent this view. The backing store is simply the grid of “pixels” that constitute the layer’s underlying appearance (before the application of transforms and animations).