xcode 如何在视图上绘制箭头？

how do I draw an arrow onto my view?

提问by serge2487

Hi there and thank you in advance for any responses. I want to draw an big wide arrow on my UIView that has a light green to dark green shade. I have been looking at documentation for CGContextRef,CGPathRef and UIBezierPath but i'm just getting more confused. Could someone please help me with this.thanks!

您好，提前感谢您的任何答复。我想在我的 UIView 上绘制一个大的宽箭头，它有一个浅绿色到深绿色的阴影。我一直在查看 CGContextRef、CGPathRef 和 UIBezierPath 的文档，但我越来越困惑。有人可以帮我解决这个问题吗？谢谢！

回答by Luca Davanzo

Question is old but I'm pleased to share you some code that I hope usefull - Swift 2.3 compatible-

问题很老，但我很高兴与您分享一些我希望有用的代码 - Swift 2.3 兼容-

public extension UIView {

  public enum PeakSide: Int {
        case Top
        case Left
        case Right
        case Bottom
    }

    public func addPikeOnView(side side: PeakSide, size: CGFloat = 10.0) {
        self.layoutIfNeeded()
        let peakLayer = CAShapeLayer()
        var path: CGPathRef?
        switch side {
        case .Top:
            path = self.makePeakPathWithRect(self.bounds, topSize: size, rightSize: 0.0, bottomSize: 0.0, leftSize: 0.0)
        case .Left:
            path = self.makePeakPathWithRect(self.bounds, topSize: 0.0, rightSize: 0.0, bottomSize: 0.0, leftSize: size)
        case .Right:
            path = self.makePeakPathWithRect(self.bounds, topSize: 0.0, rightSize: size, bottomSize: 0.0, leftSize: 0.0)
        case .Bottom:
            path = self.makePeakPathWithRect(self.bounds, topSize: 0.0, rightSize: 0.0, bottomSize: size, leftSize: 0.0)
        }
        peakLayer.path = path
        let color = (self.backgroundColor ?? .clearColor()).CGColor
        peakLayer.fillColor = color
        peakLayer.strokeColor = color
        peakLayer.lineWidth = 1
        peakLayer.position = CGPoint.zero
        self.layer.insertSublayer(peakLayer, atIndex: 0)
    }


    func makePeakPathWithRect(rect: CGRect, topSize ts: CGFloat, rightSize rs: CGFloat, bottomSize bs: CGFloat, leftSize ls: CGFloat) -> CGPathRef {
        //                      P3
        //                    /    \
        //      P1 -------- P2     P4 -------- P5
        //      |                               |
        //      |                               |
        //      P16                            P6
        //     /                                 \
        //  P15                                   P7
        //     \                                 /
        //      P14                            P8
        //      |                               |
        //      |                               |
        //      P13 ------ P12    P10 -------- P9
        //                    \   /
        //                     P11

        let centerX = rect.width / 2
        let centerY = rect.height / 2
        var h: CGFloat = 0
        let path = CGPathCreateMutable()
        var points: [CGPoint] = []
        // P1
        points.append(CGPointMake(rect.origin.x, rect.origin.y))
        // Points for top side
        if ts > 0 {
            h = ts * sqrt(3.0) / 2
            let x = rect.origin.x + centerX
            let y = rect.origin.y
            points.append(CGPointMake(x - ts, y))
            points.append(CGPointMake(x, y - h))
            points.append(CGPointMake(x + ts, y))
        }

        // P5
        points.append(CGPointMake(rect.origin.x + rect.width, rect.origin.y))
        // Points for right side
        if rs > 0 {
            h = rs * sqrt(3.0) / 2
            let x = rect.origin.x + rect.width
            let y = rect.origin.y + centerY
            points.append(CGPointMake(x, y - rs))
            points.append(CGPointMake(x + h, y))
            points.append(CGPointMake(x, y + rs))
        }

        // P9
        points.append(CGPointMake(rect.origin.x + rect.width, rect.origin.y + rect.height))
        // Point for bottom side
        if bs > 0 {
            h = bs * sqrt(3.0) / 2
            let x = rect.origin.x + centerX
            let y = rect.origin.y + rect.height
            points.append(CGPointMake(x + bs, y))
            points.append(CGPointMake(x, y + h))
            points.append(CGPointMake(x - bs, y))
        }

        // P13
        points.append(CGPointMake(rect.origin.x, rect.origin.y + rect.height))
        // Point for left side
        if ls > 0 {
            h = ls * sqrt(3.0) / 2
            let x = rect.origin.x
            let y = rect.origin.y + centerY
            points.append(CGPointMake(x, y + ls))
            points.append(CGPointMake(x - h, y))
            points.append(CGPointMake(x, y - ls))
        }

        let startPoint = points.removeFirst()
        self.startPath(path: path, onPoint: startPoint)
        for point in points {
            self.addPoint(point, toPath: path)
        }
        self.addPoint(startPoint, toPath: path)
        return path
    }

    private func startPath(path path: CGMutablePath, onPoint point: CGPoint) {
        CGPathMoveToPoint(path, nil, point.x, point.y)
    }

    private func addPoint(point: CGPoint, toPath path: CGMutablePath) {
        CGPathAddLineToPoint(path, nil, point.x, point.y)
    }

}

In this way you can call this for every kind of view:

通过这种方式，您可以为每种视图调用它：

let view = UIView(frame: frame)
view.addPikeOnView(side: .Top)

In a future I'll add offset for pike position.

将来，我将为派克位置添加偏移量。

• yes, names are definitely improvable!

• 是的，名字绝对是可以改进的！