如何使用CAShapLayer和自动布局约束绘制圆形进度条

Question

我正在使用CAShapeLayer绘制圆形进度条，只有在将其居中放置在视图上时，才能生成它。现在，我想将其约束到名片视图的后缘。下面是我的代码：

let center = cardView.center
//track layer
let trackLayer = CAShapeLayer()
let circularPath = UIBezierPath(arcCenter: center, radius: 100, startAngle: -CGFloat.pi / 2, endAngle: 2 * CGFloat.pi, clockwise: true)
trackLayer.path = circularPath.cgPath
trackLayer.strokeColor = UIColor.gray.cgColor
trackLayer.strokeEnd = 1
trackLayer.lineCap = kCALineCapRound
trackLayer.fillColor = UIColor.clear.cgColor
trackLayer.lineWidth = 5
cardView.layer.addSublayer(trackLayer)

//progress Layer
let shapeLayer = CAShapeLayer()
shapeLayer.path = circularPath.cgPath
shapeLayer.strokeColor = UIColor.yellow.cgColor
//NumberFormatter().number(from: percentageUsed) as! CGFloat
shapeLayer.strokeEnd = 0.6
shapeLayer.lineCap = kCALineCapRound
shapeLayer.fillColor = UIColor.clear.cgColor
shapeLayer.lineWidth = 5
cardView.layer.addSublayer(shapeLayer)

现在我希望我可以做类似的事情

shapeLayer.leadingAnchor.constraint(equalTo: cardVeiw.leadingAnchor, constant: 20).isActive = true