更改视图下线条的颜色

Question

如果在绿色视图下，需要重新绘制绿色线，如图：

现在如何绘制线条的示例：

func drawCurveLine(onLayer layer: CALayer, linePath: UIBezierPath, point: CurvePoint) {
    let line = CAShapeLayer()
    linePath.addCurve(to: point.endPoint, controlPoint1: point.controlPoint1, controlPoint2: point.controlPoint2)
    line.path = linePath.cgPath
    line.fillColor = nil
    line.opacity = 1.0
    line.strokeColor = UIColor.red.cgColor
    layer.addSublayer(line)
}