iOS新增绘制圆的方法实例代码

addArc(withCenter:, radius:, startAngle:, endAngle:, clockwise:)

addCurve(to:, controlPoint1:, controlPoint2:)

addArc(startPoint: , endPoint: , angle: , clockwise:)

func calculateLineLength(_ point1: CGPoint, _ point2: CGPoint) -> CGFloat {  let w = point1.x - point2.x  let h = point1.y - point2.y  return sqrt(w * w + h * h)}

func calculateAngle(point: CGPoint, origin: CGPoint) -> Double {    if point.y == origin.y {    return point.x > origin.x ? 0.0 : -Double.pi  }    if point.x == origin.x {    return point.y > origin.y ? Double.pi * 0.5 : Double.pi * -0.5  }  // Note: 修正标准坐标系角度到 iOS 坐标系  let rotationAdjustment = Double.pi * 0.5    let offsetX = point.x - origin.x  let offsetY = point.y - origin.y  // Note: 使用 -offsetY 是因为 iOS 坐标系与标准坐标系的区别  if offsetY > 0 {    return Double(atan(offsetX / -offsetY)) + rotationAdjustment  } else {    return Double(atan(offsetX / -offsetY)) - rotationAdjustment  }}

// Woring: 只计算从start到end **顺时针** 计算对应的 **小于π** 圆弧对应的圆心// Note: 计算逆时针(end到start)可以看做将传入的start和end对调后计算顺时针时的圆心位置// Note: 计算大于π的叫相当于将end和start对换后计算2π-angle的顺时针圆心位置// Note: 综上传入start，end，angle 右外部自行处理逻辑func calculateCenterFor(startPoint start: CGPoint, endPoint end: CGPoint, radian: Double) -> CGPoint {  guard radian <= Double.pi else {    fatalError("Does not support radian calculations greater than π!")  }    guard start != end else {    fatalError("Start position and end position cannot be equal!")  }    if radian == Double.pi {    let centerX = (end.x - start.x) * 0.5 + start.x    let centerY = (end.y - start.y) * 0.5 + start.y    return CGPoint(x: centerX, y: centerY)  }    let lineAB = calculateLineLength(start, end)    // 平行 Y 轴  if start.x == end.x {    let centerY = (end.y - start.y) * 0.5 + start.y    let tanResult = CGFloat(tan(radian * 0.5))    let offsetX = lineAB * 0.5 / tanResult    let centerX = start.x + offsetX * (start.y > end.y ? 1.0 : -1.0)    return CGPoint(x: centerX, y: centerY)  }    // 平行 X 轴  if start.y == end.y {    let centerX = (end.x - start.x) * 0.5 + start.x    let tanResult = CGFloat(tan(radian * 0.5))    let offsetY = lineAB * 0.5 / tanResult    let centerY = start.y + offsetY * (start.x < end.x ? 1.0 : -1.0)    return CGPoint(x: centerX, y: centerY)  }    // 普通情况    // 计算半径  let radius = lineAB * 0.5 / CGFloat(sin(radian * 0.5))  // 计算与 Y 轴的夹角  let angleToYAxis = atan(abs(start.x - end.x) / abs(start.y - end.y))  let cacluteAngle = CGFloat(Double.pi - radian) * 0.5 - angleToYAxis  // 偏移量  let offsetX = radius * sin(cacluteAngle)  let offsetY = radius * cos(cacluteAngle)    var centetX = end.x  var centerY = end.y  // 以 start 为原点判断象限区间(iOS坐标系)  if end.x > start.x && end.y < start.y {    // 第一象限    centetX = end.x + offsetX    centerY = end.y + offsetY  } else if end.x > start.x && end.y > start.y {    // 第二象限    centetX = start.x - offsetX    centerY = start.y + offsetY  } else if end.x < start.x && end.y > start.y {    // 第三象限    centetX = end.x - offsetX    centerY = end.y - offsetY  } else if end.x < start.x && end.y < start.y {    // 第四象限    centetX = start.x + offsetX    centerY = start.y - offsetY  }    return CGPoint(x: centetX, y: centerY)}

func addArc(startPoint start: CGPoint, endPoint end: CGPoint, angle: Double, clockwise: Bool) {    guard start != end && (angle >= 0 && angle <= 2 * Double.pi) else {    return  }  if angle == 0 {    move(to: start)    addLine(to: end)    return  }    var tmpStart = start, tmpEnd = end, tmpAngle = angle  // Note: 保证计算圆心时是从 start 到 end 顺时针 小于 π 的角  if tmpAngle > Double.pi {    tmpAngle = 2 * Double.pi - tmpAngle    (tmpStart, tmpEnd) = (tmpEnd, tmpStart)  }  if !clockwise {    (tmpStart, tmpEnd) = (tmpEnd, tmpStart)  }    let center = calculateCenterFor(startPoint: tmpStart, endPoint: tmpEnd, radian: tmpAngle)  let radius = calculateLineLength(start, center)    var startAngle = calculateAngle(point: start, origin: center)  var endAngle = calculateAngle(point: end, origin: center)  // Note: 逆时针绘制则交换 startAngle 和 endAngle，并且将开始点移动的 end 位置  if !clockwise {    (startAngle, endAngle) = (endAngle, startAngle)    move(to: end)  }    addArc(withCenter: center, radius: radius, startAngle: CGFloat(startAngle), endAngle: CGFloat(endAngle), clockwise: true)  move(to: end)}

override func draw(_ rect: CGRect) {    let path = UIBezierPath()  var start = CGPoint(x: 160, y: 130)  var end = CGPoint(x: 180, y: 200)  path.move(to: start)  path.addArc(startPoint: start, endPoint: end, angle: Double.pi * 1.6, clockwise: true)  path.move(to: start)  path.addArc(startPoint: start, endPoint: end, angle: Double.pi * 0.8, clockwise: true)    start = CGPoint(x: 142, y: 130)  end = CGPoint(x: 162, y: 200)  path.move(to: start)  path.addArc(startPoint: start, endPoint: end, angle: Double.pi * 0.4, clockwise: true)    start = CGPoint(x: 140, y: 130)  end = CGPoint(x: 160, y: 200)  path.move(to: start)  path.addArc(startPoint: start, endPoint: end, angle: Double.pi * 1.6, clockwise: false)  path.move(to: start)  path.addArc(startPoint: start, endPoint: end, angle: Double.pi * 0.8, clockwise: false)    path.close()  path.lineWidth = 1  UIColor.red.setStroke()  path.stroke()}

struct Angle {  private var degress: Double  static func deggess(_ degress: Double) -> Angle {    return .init(degress: degress)  }  // 弧度  var radians: Double { Double.pi * degress / 180.0 }}// Angle.deggess(90).radians // 1.570796326794897

func addArc(startPoint start: CGPoint, endPoint end: CGPoint, angle: Angle, clockwise: Bool)