核心图形绘制同心圆并填补它们之间的空白

Question

我需要绘制2个圆圈并用黄色填充内圆和外圆之间的区域，即不在交叉点的区域。我如何使用核心图形？我试过这个，但它不起作用：

   override func draw(_ rect: CGRect) {
    // Drawing code

    guard let context = UIGraphicsGetCurrentContext() else { return }

    context.setFillColor(UIColor.yellow.cgColor)

    let path = CGMutablePath()
    let radius = min(rect.width/2, rect.height/2)

    let center = CGPoint(x: rect.width/2, y: rect.height/2)
    path.addEllipse(in: CGRect(x: center.x - radius, y: center.y - radius, width: 2*radius, height: 2*radius))
    context.addPath(path)

   // context.drawPath(using: .fill)

    let path2 = CGMutablePath()
    path2.addEllipse(in: CGRect(x: center.x - radius/2, y: center.y - radius/2, width: radius, height: radius))


    context.addPath(path2)

    context.clip()

    context.drawPath(using: .fill)
}

Answer 1

您可以使用以下代码：

  let path = CGMutablePath()
    let radius = min(rect.width/2, rect.height/2)

    let center = CGPoint(x: rect.width/2, y: rect.height/2)
    path.addEllipse(in: CGRect(x: center.x - radius, y: center.y - radius, width: 2*radius, height: 2*radius))


    let path2 = CGMutablePath()
    path2.addEllipse(in: CGRect(x: center.x - radius/2, y: center.y - radius/2, width: radius, height: radius))

   path.addPath(path2)
    context.addPath(path)

    context.drawPath(using: .eoFill)


//inner part
   let path3 = CGMutablePath()
    path3.addEllipse(in: CGRect(x: center.x - radius/2, y: center.y - radius/2, width: radius, height: radius))
      context.addPath(path3)
    context.setFillColor(UIColor.green.cgColor)
context.fillPath()