Question

我试图通过传递点集来画一个循环中的多个点。但是，不会出现一个点。想法-我正在解析xml文档并提取要在视图上绘制的点。

   Edit - I have updated the code with suggested changes and it is working. 

            //View Class
            class DrawTrace: UIView
{

    var points = [CGPoint]()
    {
        didSet {
            setNeedsDisplay()
        }
    }

override  func draw(_ rect: CGRect)
    {
        let size = CGSize(width: 1, height: 1)
        UIColor.white.set()
        for point in points
        {
            print(point.x,point.y)
            let dot = UIBezierPath(ovalIn: CGRect(origin: point, size: size))

            dot.fill()
        }
    }



}
 //View Controller Class  

    class ViewController: UIViewController
    {
        var object : traceDoc =  traceDoc()
        let trace = DrawTrace(frame: CGRect(x: 0, y: 0, width: 200, height: 200))
        override func viewDidLoad()
        {

            super.viewDidLoad()
            object.collectionOfData()
            trace.points = object.tracePoints
            self.view.addSubview(trace)
        }
    }

为视图控制器中的视图层次添加了视图实例。创建了DrawTrace实例并附加到tracepoints数组。

Answer 1

看不见黑视图中的黑色点，请尝试将白色点变成白色：

shapeLayer.fillColor = UIColor.white.cgColor
shapeLayer.strokeColor = UIColor.white.cgColor

此外，在UIViewController代码中，您没有将DrawTrace添加到视图层次结构中，请尝试在viewDidLoad中进行操作：

self.view.addSubview(drawTraceInstance)

最后，似乎您必须遍历CGPoint的数组。使用数组的用户FastEnumeration代替了使用跨步：

for point in points
{
    drawDot(x: point.x, y: point.y,Color: fillColor, size: size)
}

Answer 2

您的代码比需要的复杂得多。一个大问题是，每次调用draw时，您都会添加越来越多的图层。

您无需在自定义视图中使用图层来绘制点。这是一个更简单的解决方案：

class DrawTrace: UIView
{
    var points = [CGPoint]() {
        didSet {
            setNeedsDisplay()
        }
    }

    override func draw(_ rect: CGRect)
    {
        let size = CGSize(width: 2, height: 2)

        UIColor.black.set()
        for point in points {
            let dot = UIBezierPath(ovalIn: CGRect(origin: point, size: size))
            // this just draws the circle by filling it.
            // Update any properties of the path as needed.
            // Use dot.stroke() if you need an outline around the circle.
            dot.fill()
        }
    }
}

let trace = DrawTrace(frame: CGRect(x: 0, y: 0, width: 200, height: 200))
trace.backgroundColor = .white
trace.points = [ CGPoint(x: 10, y: 10), CGPoint(x: 35, y: 100)]

以上内容可以复制到游乐场。

Swift：循环画点

2 个答案: