Interface Structure

Parent page: Design

• There is one UIScreen which has one UIWindow which has one or more UIView, each can have one or more UIView and so on.
• Each UIScreen, UIWindow, and UIView has one CALayer attached to it.
• UIView is CALayer wrapper, CALayer is CGLayer wrapper, CGLayer is CGContext wrapper, and CGContext comes from the Window Context. The main function of each of these classes, is as following:
  • UIView: handles the user events.
  • CALayer: handles animations.
  • CGLayer: handles drawing offline then later putting it on the Window Context.
  • CGContext: hold the drawing instructions and bitmap images of the layer.