Tukukkk

I am having trouble flipping an arc using core graphics api in a UIView.

I understand that the coordinate system is different. UIkit helps me half way by transforming the coordinate system to accommodate the center I provide into a core graphic coordination system. I am assuming that when I draw an arc using core graphics api that its drawing the arc by using the core graphics coordinate system?

I can just change clockwise to false and it will give me what I need. Is this good practice?

I was playing around with CGAffineTransform’s rotation and scale, it didn’t give me what I need. Any way to flip the arc around without hawkishly changing clocking to false?

I also used UIBezierPath to draw another arc the way I want it. As I understand, UIBezierPath is a wrapper around CoreGraphics. I would like to know how I can do this using pure CoreGraphics API.

Extra question: My last function
Call path.stroke() paints the UIBezierPath path and the CGPath arcPath1. How come? 0.o

override func draw(_ rect: CGRect) {

    guard let CGContext = UIGraphicsGetCurrentContext() else { return }

    let boxPath = CGMutablePath()



    boxPath.addLines(between:

    [CGPoint(x: rect.width / 2, y: rect.height),

     CGPoint(x: rect.width / 2, y: rect.height / 2),

     CGPoint(x: rect.width, y: rect.height / 2)])



    CGContext.beginPath() // begin new path

    CGContext.addPath(boxPath.copy(strokingWithWidth: 5.0, lineCap: .square, lineJoin: .round, miterLimit: 0)) // add new path



    CGContext.setFillColor(UIColor.blue.cgColor)

    CGContext.fillPath()



    let arcPath1 = CGMutablePath()

    arcPath1.addArc(center: CGPoint(x: rect.width / 4, y: rect.height / 4 * 3),

                    radius: 20.0,

                    startAngle: CGFloat(180).degreesToRadians,

                    endAngle: CGFloat(360).degreesToRadians,

                    clockwise: true,

                    transform: CGAffineTransform(rotationAngle: CGFloat(0).degreesToRadians))





    CGContext.beginPath()

    CGContext.addPath(arcPath1)

    CGContext.setStrokeColor(UIColor.blue.cgColor)



    let path = UIBezierPath(arcCenter: CGPoint(x: rect.width / 4 * 3, y: rect.height / 4 * 3),

                            radius: 20.0,

                            startAngle: CGFloat(180).degreesToRadians,

                            endAngle: CGFloat(360).degreesToRadians,

                            clockwise: true)



    path.lineWidth = 5.0

    path.stroke()

}

Arcs, left: CG, right: Bezier