A test project of drawing and erasing
I want to test some pen drawing and erasing snippets in this project.
- Use the UIBezierPath and addQuadCurve to generate the curve line
- Use the mask to implement the eraser
- Combine the sublayers lower down the CPU usage
ref: https://medium.com/@almalehdev/high-performance-drawing-on-ios-part-1-f3a24a0dcb31