Swift 3.0 以相同的起点和终点角度绘制圆结果为直线

Question

我写了下面的代码来绘制一个带有整体的矩形：

fileprivate let strokeWidth: CGFloat = 5

let shapeLayer = CAShapeLayer()
shapeLayer.strokeColor = UIColor.white.cgColor
shapeLayer.lineWidth = strokeWidth
shapeLayer.fillColor = UIColor(white: 0.5, alpha: 0.9).cgColor

let p = UIBezierPath(rect: bounds.insetBy(dx: -strokeWidth, dy: -strokeWidth))
let radius = bounds.size.width / 3
p.move(to: CGPoint(x: bounds.midX + radius, y: bounds.midY))
p.addArc(withCenter: CGPoint(x: bounds.midX, y: bounds.midY), radius: radius, startAngle: 0, endAngle: CGFloat(2 * Double.pi), clockwise: false)
p.close()
shapeLayer.path = p.cgPath

layer.addSublayer(shapeLayer)

这里的问题是这一行：

p.addArc(withCenter: CGPoint(x: bounds.midX, y: bounds.midY), radius: radius, startAngle: 0, endAngle: CGFloat(2 * Double.pi), clockwise: false)

打印出路径的描述： UIBezierPath: 0x6000000b35c0; MoveTo {-5, -5}, LineTo {380, -5}, LineTo {380, 672}, LineTo {-5, 672}, 关闭, MoveTo {312.5, 333.5}, LineTo {312.5, 333.49999999999994}, 关闭

如您所见，最后两个条目是 lineTo 和 close，这不是我预期的结果（一个完整的圆圈），我什么也得不到，因为 333.5 和 333.4999999 之间的线太短了。

自切换到 Swift 3 后出现此问题，在 Objective-C 中这不是问题。

将结束角度更改为 1.9 * Double.pi 也可以，不知道为什么。但是完整的圆应该有 2 * Double.pi.

有什么想法还是 Swift 3 错误？

Answer 1

这样试试：

let bounds = UIScreen.main.bounds
let strokeWidth: CGFloat = 5
let shapeLayer = CAShapeLayer()
shapeLayer.strokeColor = UIColor.white.cgColor
shapeLayer.lineWidth = strokeWidth
shapeLayer.fillColor = UIColor(white: 0.5, alpha: 0.9).cgColor
let p = UIBezierPath(rect: bounds.insetBy(dx: -strokeWidth, dy: -strokeWidth))
let radius = bounds.size.width / 3
p.move(to: CGPoint(x: bounds.midX + radius, y: bounds.midY))
p.addArc(withCenter: CGPoint(x: bounds.midX, y: bounds.midY), radius: radius, startAngle: 2 * .pi, endAngle: 0, clockwise: false)
p.close()
shapeLayer.fillColor = UIColor.red.cgColor
shapeLayer.strokeColor = UIColor.black.cgColor
shapeLayer.lineWidth = 5
shapeLayer.path = p.cgPath
let view = UIView(frame: bounds)
view.backgroundColor = .yellow
view.layer.addSublayer(shapeLayer)

view

Swift 3.0 以相同的起点和终点角度绘制圆结果为直线

Swift 3.0 draw circle with same start and end angle results in line

drawing

ios

uibezierpath

swift3