CustomDrawingView.swift

    override func draw(_ rect: CGRect) {
        UIColor.white.setFill()
        
        let minX: CGFloat = 0
        let maxX = rect.width
        let maxY = rect.height
        let midX = rect.midX

        let circleRadius: CGFloat = 45
        let roundingRadius: CGFloat = 6
        
        let path = UIBezierPath()
        
        path.move(to: CGPoint(x: minX, y: circleRadius))
        path.addArc(withCenter: CGPoint(x: midX - circleRadius - roundingRadius, y: circleRadius - roundingRadius), radius: roundingRadius, startAngle: CGFloat.pi/2, endAngle: 0, clockwise: false)
        path.addArc(withCenter: CGPoint(x: midX, y: circleRadius), radius: circleRadius, startAngle: CGFloat.pi + tan(roundingRadius/circleRadius), endAngle: CGFloat.pi * 2 - tan(roundingRadius/circleRadius), clockwise: true)
        path.addArc(withCenter: CGPoint(x: midX + circleRadius + roundingRadius, y: circleRadius - roundingRadius), radius: roundingRadius, startAngle: CGFloat.pi, endAngle: CGFloat.pi/2, clockwise:false)
        path.addLine(to: CGPoint(x: maxX, y: circleRadius))
        path.addLine(to: CGPoint(x: maxX, y: maxY))
        path.addLine(to: CGPoint(x: minX, y: maxY))
        
        path.close()
        path.fill()
    }