draw an arc from endpoints of line and fill in - swift

Question

I did the following:
let xOrigin = (pointsOfPerformance[POP.gluteusMaximus.index].x_origin / 375) * self.view.bounds.width
let yOrigin = (pointsOfPerformance[POP.gluteusMaximus.index].y_origin / 666.6666) * (self.view.bounds.width * 16 / 9)
let p0 = CGPoint(x: xOrigin, y: yOrigin)
let xDest = (pointsOfPerformance[POP.upperBack.index].x_origin / 375) * self.view.bounds.width
let yDest = (pointsOfPerformance[POP.upperBack.index].y_origin / 666.6666) * (self.view.bounds.width * 16 / 9)
let p1 = CGPoint(x: xDest, y: yDest)
let midPoint = CGPoint(x: (xOrigin + xDest) / 2, y:
(yOrigin + yDest) / 2)
let path = UIBezierPath()
path.move(to: p0)
path.addLine(to: p1)
path.addArc(withCenter: p2, radius: 94, startAngle: 200, endAngle: 130, clockwise: true)
let centerOfCircle = makePoint(xOffset: p2.x, yOffset: p2.y)
view.addSubview(centerOfCircle)
let shapeLayer = CAShapeLayer()
shapeLayer.path = path.cgPath
shapeLayer.fillColor = UIColor.animationRed.cgColor
shapeLayer.strokeColor = UIColor.animationRed.cgColor
shapeLayer.lineWidth = 0.05
view.layer.addSublayer(shapeLayer)
How do I get the circle to only show up as a slice of its curve that comes off the line on the back. It's unclear how I manipulate the function to get only the part coming off the line on the back visible.

Answer 1

This works on MacOS:
class CustomView: NSView {
override func draw(_ rect: CGRect) {
let bkgrnd = NSBezierPath(rect: rect)
let fillColor = NSColor.white
fillColor.set()
bkgrnd.fill()
let center = NSMakePoint(rect.size.width/2,rect.size.height/2)
let radius:CGFloat = rect.size.width/4
let path1 = NSBezierPath()
path1.appendArc(withCenter: center, radius: radius, startAngle: 90, endAngle: 270)
NSColor.gray.set()
path1.fill()
let path2 = NSBezierPath()
path2.appendArc(withCenter: center, radius: radius, startAngle: 270, endAngle: 90)
NSColor.blue.set()
path2.fill()
}
}

Answer 2

Demonstrates getting a small slice of the periphery of a circle for MacOS:
class CustomView: NSView {
override func draw(_ rect: CGRect ) {
let bkgrnd = NSBezierPath(rect: rect)
let fillColor = NSColor.white
fillColor.set()
bkgrnd.fill()
let center = NSMakePoint(rect.size.width/2,rect.size.height/2)
let radius:CGFloat = rect.size.width/4
let circle = NSBezierPath()
circle.appendArc(withCenter: center, radius: radius, startAngle: 0, endAngle: 360)
NSColor.gray.set()
circle.fill()
let arc = NSBezierPath()
arc.appendArc(withCenter: center, radius: radius, startAngle: 120, endAngle: 200)
NSColor.blue.set()
arc.fill()
}
}