如何制作三角形的UIView？

Question

我是Swift的新手。我的应用程序中有一个常规的矩形UIView，我试图使其变为三角形，以便用户可以在边界内绘制。

有什么建议吗？我正在使用UIKit，并希望避免使用SpriteKit。

谢谢！

Answer 1

Result triangles

swift5中的代码

//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)
    }
}