Ios 带外部笔划的圆形进度视图

您可以用简单的蒙版减go 中间的圆圈，如下所示:

let maskLayer = CAShapeLayer()
maskLayer.path = UIBezierPath(rect: self.bounds).cgPath.subtracting(circlePath.cgPath)
layer.mask = maskLayer

完整的工作代码:

class CircularProgressBarView: UIView {
    var progress: CGFloat = 0 { didSet { layoutSubviews() } }
    var progressLineWidth: CGFloat = 20 { didSet { layoutSubviews() } }
    var progressColor = UIColor.green { didSet { layoutSubviews() } }
    var pattern: [NSNumber] = [4,4] { didSet { layoutSubviews() } }

    private var customLayer = CALayer()

    override func layoutSubviews() {
        super.layoutSubviews()

        customLayer.removeFromSuperlayer()
        customLayer = CALayer()

        let bounds = CGRect(
            x: progressLineWidth,
            y: progressLineWidth,
            width: bounds.width - progressLineWidth*2,
            height: bounds.height - progressLineWidth*2
        )

        let circlePath = UIBezierPath(ovalIn: bounds)

        let trackLayer = CAShapeLayer()
        trackLayer.path = circlePath.cgPath
        trackLayer.strokeColor = UIColor.gray.cgColor
        trackLayer.lineWidth = progressLineWidth
        trackLayer.lineDashPattern = pattern
        trackLayer.fillColor = UIColor.red.cgColor
        customLayer.addSublayer(trackLayer)

        let progressLayer = CAShapeLayer()
        progressLayer.path = circlePath.cgPath
        progressLayer.fillColor = UIColor.clear.cgColor
        progressLayer.strokeColor = progressColor.cgColor
        progressLayer.lineWidth = progressLineWidth * 2
        progressLayer.strokeEnd = progress
        progressLayer.lineDashPattern = pattern
        customLayer.addSublayer(progressLayer)

        let containerPath = UIBezierPath(rect: self.bounds).cgPath
        let maskLayer = CAShapeLayer()
        maskLayer.path = containerPath.subtracting(circlePath.cgPath)
        customLayer.mask = maskLayer

        layer.addSublayer(customLayer)
    }
}

_{当然，您可以旋转整个图层(或视图)，使其从12点开始}