Purpose of CALayer?

问题:

I'm slightly used as to what the purpose of CALayer's existence is. Why not just put the properties in a UIView?

Thanks.

回答1:

A CALayer represents a completely different "thing" from a UIView. A CALayer only deals with drawing itself, and encapsulating the information needed to do that. A view, on the other hand, owns one or many layers, which it uses to draw itself. A view has many other functions and properties though, that are unrelated to its representation on the screen.

I would recommend digging into the Apple documentation, and maybe picking up a book on Object Oriented coding.