问如何在swift中创建虚线？

EN

let  path = UIBezierPath()

let  p0 = CGPoint(x: self.bounds.minX, y: self.bounds.midY)
path.move(to: p0)

let  p1 = CGPoint(x: self.bounds.maxX, y: self.bounds.midY)
path.addLine(to: p1)

let  dashes: [ CGFloat ] = [ 16.0, 32.0 ]
path.setLineDash(dashes, count: dashes.count, phase: 0.0)

path.lineWidth = 8.0
path.lineCapStyle = .butt
UIColor.magenta.set()
path.stroke()

let  path = UIBezierPath()

let  p0 = CGPointMake(CGRectGetMinX(self.bounds), CGRectGetMidY(self.bounds))
path.moveToPoint(p0)

let  p1 = CGPointMake(CGRectGetMaxX(self.bounds), CGRectGetMidY(self.bounds))
path.addLineToPoint(p1)

let  dashes: [ CGFloat ] = [ 0.0, 16.0 ]
path.setLineDash(dashes, count: dashes.count, phase: 0.0)
path.lineWidth = 8.0
path.lineCapStyle = .Round
UIColor.magentaColor().set()
path.stroke()

let  context: CGContext = UIGraphicsGetCurrentContext()!

let  p0 = CGPointMake(CGRectGetMinX(self.bounds), CGRectGetMidY(self.bounds))
CGContextMoveToPoint(context, p0.x, p0.y)

let  p1 = CGPointMake(CGRectGetMaxX(self.bounds), CGRectGetMidY(self.bounds))
CGContextAddLineToPoint(context, p1.x, p1.y)

let  dashes: [ CGFloat ] = [ 16.0, 32.0 ]
CGContextSetLineDash(context, 0.0, dashes, dashes.count)

CGContextSetLineWidth(context, 8.0)
CGContextSetLineCap(context, .Butt)
UIColor.blueColor().set()
CGContextStrokePath(context)

import UIKit

public class DashedView: UIView {

    public struct Configuration {
        public var color: UIColor
        public var dashLength: CGFloat
        public var dashGap: CGFloat

        public init(
            color: UIColor,
            dashLength: CGFloat,
            dashGap: CGFloat) {
            self.color = color
            self.dashLength = dashLength
            self.dashGap = dashGap
        }

        static let `default`: Self = .init(
            color: .lightGray,
            dashLength: 7,
            dashGap: 3)
    }

    // MARK: - Properties

    /// Override to customize height
    public class var lineHeight: CGFloat { 1.0 }

    override public var intrinsicContentSize: CGSize {
        CGSize(width: UIView.noIntrinsicMetric, height: Self.lineHeight)
    }

    public final var config: Configuration = .default {
        didSet {
            drawDottedLine()
        }
    }

    private var dashedLayer: CAShapeLayer?

    // MARK: - Life Cycle

    override public func layoutSubviews() {
        super.layoutSubviews()

        // We only redraw the dashes if the width has changed.
        guard bounds.width != dashedLayer?.frame.width else { return }

        drawDottedLine()
    }

    // MARK: - Drawing

    private func drawDottedLine() {
        if dashedLayer != nil {
            dashedLayer?.removeFromSuperlayer()
        }

        dashedLayer = drawDottedLine(
            start: bounds.origin,
            end: CGPoint(x: bounds.width, y: bounds.origin.y),
            config: config)
    }

}

// Thanks to: https://stackoverflow.com/a/49305154/4802021
private extension DashedView {
    func drawDottedLine(
        start: CGPoint,
        end: CGPoint,
        config: Configuration) -> CAShapeLayer {
        let shapeLayer = CAShapeLayer()
        shapeLayer.strokeColor = config.color.cgColor
        shapeLayer.lineWidth = Self.lineHeight
        shapeLayer.lineDashPattern = [config.dashLength as NSNumber, config.dashGap as NSNumber]

        let path = CGMutablePath()
        path.addLines(between: [start, end])
        shapeLayer.path = path
        layer.addSublayer(shapeLayer)

        return shapeLayer
    }
}

extension UIView {

    func createDashedLine(from point1: CGPoint, to point2: CGPoint, color: UIColor, strokeLength: NSNumber, gapLength: NSNumber, width: CGFloat) {
        let shapeLayer = CAShapeLayer()

        shapeLayer.strokeColor = color.cgColor
        shapeLayer.lineWidth = width
        shapeLayer.lineDashPattern = [strokeLength, gapLength]

        let path = CGMutablePath()
        path.addLines(between: [point1, point2])
        shapeLayer.path = path
        layer.addSublayer(shapeLayer)
    }
}

let topPoint = CGPoint(x: view.frame.midX, y: view.bounds.minY)
let bottomPoint = CGPoint(x: view.frame.midX, y: view.bounds.maxY)

view.createDashedLine(from: topPoint, to: bottomPoint, color: .black, strokeLength: 4, gapLength: 6, width: 2)