Swift : 循环绘制点

Question

我试图通过传递一组点来循环绘制多个点。但是没有一个点被绘制在视图上。想法 - 我正在解析 xml 文档并提取点以在视图中绘制它。

   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)
        }
    }

将视图实例添加到视图层次结构中，该视图层次结构位于 DrawTrace 的视图 controller.Created 实例中并附加到跟踪点数组。

Answer 1

黑色视图中的黑点不可见，请尝试将点设为白色：

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:

self.view.addSubview(drawTraceInstance)

最后，您似乎必须遍历 CGPoint 数组。用户 FastEnumeration over Array:

而不是使用 stride

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，您都会不断添加越来越多的层。

无需使用图层在自定义视图中绘制点。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)]

以上可以复制到playground中。

Swift : 循环绘制点

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swift