向 UIBezierPath addArc 函数添加箭头末端答案

【问题标题】：Add an arrow end to the UIBezierPath addArc function向 UIBezierPath addArc 函数添加箭头末端
【发布时间】：2020-08-28 20:36:06
【问题描述】：

我正在尝试实现以下结果，直到 UIBezierPath 弧的末尾：

我找到了一个类似的答案here，但是它没有利用addArc函数，所以我不能设置开始和结束角度，写在obj-c上。

【问题讨论】：

标签： swift core-graphics uibezierpath

【解决方案1】：

extension UIBezierPath {
    func addArrow(start: CGPoint, end: CGPoint, pointerLineLength: CGFloat, arrowAngle: CGFloat) {
        self.move(to: start)
        self.addLine(to: end)

        let startEndAngle = atan((end.y - start.y) / (end.x - start.x)) + ((end.x - start.x) < 0 ? CGFloat(Double.pi) : 0)
        let arrowLine1 = CGPoint(x: end.x + pointerLineLength * cos(CGFloat(Double.pi) - startEndAngle + arrowAngle), y: end.y - pointerLineLength * sin(CGFloat(Double.pi) - startEndAngle + arrowAngle))
        let arrowLine2 = CGPoint(x: end.x + pointerLineLength * cos(CGFloat(Double.pi) - startEndAngle - arrowAngle), y: end.y - pointerLineLength * sin(CGFloat(Double.pi) - startEndAngle - arrowAngle))

        self.addLine(to: arrowLine1)
        self.move(to: end)
        self.addLine(to: arrowLine2)
    }
    
}

用法：

    path.addArc(withCenter: center, radius: radius,
                startAngle: angle1Inradians, endAngle: angle2Inradians,
                    clockwise: false)

    let pathCurrentPoint = path.currentPoint
    let x = center.x + radius * cos(angle1Inradians)
    let y = center.y - radius * sin(angle2Inradians)
    let point = CGPoint(x: x , y: y )
    path.addArrow(start: pathCurrentPoint, end: point, pointerLineLength: 10, arrowAngle: CGFloat(Double.pi / 4))

    let layer = CAShapeLayer()
    layer.fillColor = UIColor.clear.cgColor
    layer.lineWidth = 2
    layer.strokeColor = UIColor.orange.cgColor
    layer.path = path.cgPath
    self.layer.addSublayer(layer)

【讨论】：