By default, a view’s shadow inherits a path that outlines its content. However, you can change the path of a shadow like this:
view.shadow.path = shape.path
Typically, you will create a shape object and use its path.
let c = Circle(center: canvas.center, radius: 100)
c.shadow.opacity = 0.4
c.shadow.radius = 3.0
c.shadow.offset = Size(130, 130)
let s = Star(center: Point(), pointCount: 40, innerRadius: 99, outerRadius: 105)
c.shadow.path = s.path
self.canvas.add(c)