Ios 在Swift中使用UIBezierPath创建三角形

我正在尝试理解如何用Swift创建三角形。我发现这个代码创建了一个三角形

class TriangleLayer: CAShapeLayer {

  let innerPadding: CGFloat = 30.0  

  override init() {
    super.init()
    fillColor = Colors.red.CGColor
    strokeColor = Colors.red.CGColor
    lineWidth = 7.0
    lineCap = kCALineCapRound
    lineJoin = kCALineJoinRound
    path = trianglePathSmall.CGPath
  }

  required init?(coder aDecoder: NSCoder) {
    fatalError("init(coder:) has not been implemented")
  }

  var trianglePathSmall: UIBezierPath {
     let trianglePath = UIBezierPath()
     trianglePath.moveToPoint(CGPoint(x: 5.0 + innerPadding, y: 95.0))     // #1
     trianglePath.addLineToPoint(CGPoint(x: 50.0, y: 12.5 + innerPadding)) // #2
     trianglePath.addLineToPoint(CGPoint(x: 95.0 - innerPadding, y: 95.0)) // #3
     trianglePath.closePath()
     return trianglePath
 }

这个代码创建了一个这样的形状 在屏幕中部。

我试着调整和玩弄它，以了解它是如何工作的；然而，在这一点上，我意识到，我迷失了相当多的逻辑。我将上面三角形的CG点放在我头部的x-y轴上，看起来像：

 #1 x:35, y:95          #3 x:65, y:95
           #2 x:50, y: 42.5 

 #1 x:35, y:95          #3 x:65, y:95
           #2 x:50, y: 147.5 

但是如果我把点放在x-y轴上，三角形是颠倒的

我想要实现的是轴心国告诉我的，我想要实现

         .   .                                .
                 <like this.   not this> 
           .                                .   .

---

你只是把斧头倒过来。坐标系从0,0开始，在X方向向右延伸，在Y方向向下延伸

所以你的观点是：

           #2 x:50, y: 42.5 
 #1 x:35, y:95          #3 x:65, y:95

要获得所需的三角形，您需要：

 #1 x:35, y:95          #3 x:65, y:95
           #2 x:50, y: 42.5 

 #1 x:35, y:95          #3 x:65, y:95
           #2 x:50, y: 147.5 

---

你只是把斧头倒过来。坐标系从0,0开始，在X方向向右延伸，在Y方向向下延伸

所以你的观点是：

           #2 x:50, y: 42.5 
 #1 x:35, y:95          #3 x:65, y:95

要获得所需的三角形，您需要：

 #1 x:35, y:95          #3 x:65, y:95
           #2 x:50, y: 42.5 

 #1 x:35, y:95          #3 x:65, y:95
           #2 x:50, y: 147.5 

斯威夫特4*

使用AutoLayout执行此操作的最简单方法是：

打开故事板并在UIViewController中拖动UIView，将其定位，然后根据需要设置大小，这就是三角形的位置。将视图背景设置为透明。 创建一个新类，你可以随意命名我的名为TriangleView。这将是该课程的内容： 类TriangleView:UIView{

转到情节提要，选择UIView并在Identity Inspector中编写类名TriangleView

享受你的三角

斯威夫特4*

使用AutoLayout执行此操作的最简单方法是：

打开故事板并在UIViewController中拖动UIView，将其定位，然后根据需要设置大小，即三角形所在的位置。将视图背景设置为透明。 创建一个新类，您可以根据需要命名它。我将其命名为mine TriangleView。这将是该类的内容： 类TriangleView:UIView{

转到情节提要，选择UIView并在Identity Inspector中编写类名TriangleView

享受你的三角

swift5代码

//TriangleView

extension UIView {

    func setRightTriangle(targetView:UIView?){
        let heightWidth = targetView!.frame.size.width //you can use triangleView.frame.size.height
        let path = CGMutablePath()

        path.move(to: CGPoint(x: heightWidth/2, y: 0))
        path.addLine(to: CGPoint(x:heightWidth, y: heightWidth/2))
        path.addLine(to: CGPoint(x:heightWidth/2, y:heightWidth))
        path.addLine(to: CGPoint(x:heightWidth/2, y:0))

        let shape = CAShapeLayer()
        shape.path = path
        shape.fillColor = UIColor.blue.cgColor

        targetView!.layer.insertSublayer(shape, at: 0)
    }

    func setLeftTriangle(targetView:UIView?){
        let heightWidth = targetView!.frame.size.width
        let path = CGMutablePath()

        path.move(to: CGPoint(x: heightWidth/2, y: 0))
        path.addLine(to: CGPoint(x:0, y: heightWidth/2))
        path.addLine(to: CGPoint(x:heightWidth/2, y:heightWidth))
        path.addLine(to: CGPoint(x:heightWidth/2, y:0))

        let shape = CAShapeLayer()
        shape.path = path
        shape.fillColor = UIColor.blue.cgColor

        targetView!.layer.insertSublayer(shape, at: 0)
    }

    func setUpTriangle(targetView:UIView?){
     let heightWidth = targetView!.frame.size.width
        let path = CGMutablePath()

        path.move(to: CGPoint(x: 0, y: heightWidth))
        path.addLine(to: CGPoint(x:heightWidth/2, y: heightWidth/2))
        path.addLine(to: CGPoint(x:heightWidth, y:heightWidth))
        path.addLine(to: CGPoint(x:0, y:heightWidth))

        let shape = CAShapeLayer()
        shape.path = path
        shape.fillColor = UIColor.blue.cgColor

        targetView!.layer.insertSublayer(shape, at: 0)
    }

    func setDownTriangle(targetView:UIView?){
        let heightWidth = targetView!.frame.size.width
        let path = CGMutablePath()

        path.move(to: CGPoint(x: 0, y: 0))
        path.addLine(to: CGPoint(x:heightWidth/2, y: heightWidth/2))
        path.addLine(to: CGPoint(x:heightWidth, y:0))
        path.addLine(to: CGPoint(x:0, y:0))

        let shape = CAShapeLayer()
        shape.path = path
        shape.fillColor = UIColor.blue.cgColor

        targetView!.layer.insertSublayer(shape, at: 0)
    }
}

swift5代码

//TriangleView

extension UIView {

    func setRightTriangle(targetView:UIView?){
        let heightWidth = targetView!.frame.size.width //you can use triangleView.frame.size.height
        let path = CGMutablePath()

        path.move(to: CGPoint(x: heightWidth/2, y: 0))
        path.addLine(to: CGPoint(x:heightWidth, y: heightWidth/2))
        path.addLine(to: CGPoint(x:heightWidth/2, y:heightWidth))
        path.addLine(to: CGPoint(x:heightWidth/2, y:0))

        let shape = CAShapeLayer()
        shape.path = path
        shape.fillColor = UIColor.blue.cgColor

        targetView!.layer.insertSublayer(shape, at: 0)
    }

    func setLeftTriangle(targetView:UIView?){
        let heightWidth = targetView!.frame.size.width
        let path = CGMutablePath()

        path.move(to: CGPoint(x: heightWidth/2, y: 0))
        path.addLine(to: CGPoint(x:0, y: heightWidth/2))
        path.addLine(to: CGPoint(x:heightWidth/2, y:heightWidth))
        path.addLine(to: CGPoint(x:heightWidth/2, y:0))

        let shape = CAShapeLayer()
        shape.path = path
        shape.fillColor = UIColor.blue.cgColor

        targetView!.layer.insertSublayer(shape, at: 0)
    }

    func setUpTriangle(targetView:UIView?){
     let heightWidth = targetView!.frame.size.width
        let path = CGMutablePath()

        path.move(to: CGPoint(x: 0, y: heightWidth))
        path.addLine(to: CGPoint(x:heightWidth/2, y: heightWidth/2))
        path.addLine(to: CGPoint(x:heightWidth, y:heightWidth))
        path.addLine(to: CGPoint(x:0, y:heightWidth))

        let shape = CAShapeLayer()
        shape.path = path
        shape.fillColor = UIColor.blue.cgColor

        targetView!.layer.insertSublayer(shape, at: 0)
    }

    func setDownTriangle(targetView:UIView?){
        let heightWidth = targetView!.frame.size.width
        let path = CGMutablePath()

        path.move(to: CGPoint(x: 0, y: 0))
        path.addLine(to: CGPoint(x:heightWidth/2, y: heightWidth/2))
        path.addLine(to: CGPoint(x:heightWidth, y:0))
        path.addLine(to: CGPoint(x:0, y:0))

        let shape = CAShapeLayer()
        shape.path = path
        shape.fillColor = UIColor.blue.cgColor

        targetView!.layer.insertSublayer(shape, at: 0)
    }
}

---

这是苹果公司的二维绘图文档。0,0在左上角，Y轴向下递增。这是苹果公司的二维绘图文档。0,0在左上角，Y轴向下递增。