Learn more about paths: how to use them as clipping areas and how to use them to outline CAShapeLayers. Then learn the difference between points and pixels.
It would be great if the video mentioned why startAngle is Pi and endAngle is 0 (because of the coordinate system iOS uses?).
@chenglu - great comment.
The default coordinate system is based on an upside down standard unit circle.
Here’s the standard unit circle:
And here’s Apple’s unit circle:
When we specify clockwise in the arc’s function call, we go in a clockwise direction, so 90 degrees (or π / 2) is at the bottom.
In the video I went clockwise from π to 0. But equally I could have gone anti-clockwise from 0 to π.
I had two questions I was hoping to get help with:
I noticed in the second curve you add to the point, the line width is multiplied by two, whereas the previous curve used the line width by itself. Is there a reason to this that I am missing?
Secondly, is there a reason we are using CAShapeLayer vs just drawing over whatever was previously drawn in Core Graphics?
