在Swift中的UIView上绘制网格

Question

我对Swift非常陌生。我正在尝试在Swift中的UIView上绘制网格（如图形页面）。该代码正在运行，但是我看不到任何行。我看不到我做错了。

在情节提要中，我在ViewController上添加了一个视图。

在代码中，我创建了GridView.swift并将其添加到上面的视图中。这是GridView类的代码。正在调用函数draw，并且代码运行无任何错误。它只是按照我的想法去做。

甚至都没有画一条线（我删除了for循环，只想画一条线）。这似乎很基础，应该可以使用。

import Foundation
import UIKit

class GridView: UIView 
{
    fileprivate var gridWidthMultiple: CGFloat
    {
        return 10
    }
    fileprivate var gridHeightMultiple : CGFloat
    {
        return 20
    }

    fileprivate var gridWidth: CGFloat
    {   
        return bounds.width/CGFloat(gridWidthMultiple)
    }

    fileprivate var gridHeight: CGFloat
    {
        return bounds.height/CGFloat(gridHeightMultiple)
    }

    fileprivate var gridCenter: CGPoint {
        return CGPoint(x: bounds.midX, y: bounds.midY)
    }

    fileprivate func drawGrid()
    {
        let path = UIBezierPath()
        path.lineWidth = 5.0

        for index in 1...Int(gridWidthMultiple) - 1
        {
            let start = CGPoint(x: CGFloat(index) * gridWidth, y: 0)
            let end = CGPoint(x: CGFloat(index) * gridWidth, y:bounds.height)
            path.move(to: start)
            path.addLine(to: end)
        }
    }

    override func draw(_ rect: CGRect)
    {
        drawGrid()
    }
}

Answer 1

只需复制并粘贴以下代码，您就可以开始了。我没有检查您绘制正确网格的逻辑，我刚刚解决了不绘制问题。如果它绘制了错误的网格，那么我现在将重新检查您的网格逻辑，它仅可以帮助您使用UIBezierPath

进行绘制

class GridView: UIView
{
    private var path = UIBezierPath()
    fileprivate var gridWidthMultiple: CGFloat
    {
        return 10
    }
    fileprivate var gridHeightMultiple : CGFloat
    {
        return 20
    }

    fileprivate var gridWidth: CGFloat
    {
        return bounds.width/CGFloat(gridWidthMultiple)
    }

    fileprivate var gridHeight: CGFloat
    {
        return bounds.height/CGFloat(gridHeightMultiple)
    }

    fileprivate var gridCenter: CGPoint {
        return CGPoint(x: bounds.midX, y: bounds.midY)
    }

    fileprivate func drawGrid()
    {
        path = UIBezierPath()
        path.lineWidth = 5.0

        for index in 1...Int(gridWidthMultiple) - 1
        {
            let start = CGPoint(x: CGFloat(index) * gridWidth, y: 0)
            let end = CGPoint(x: CGFloat(index) * gridWidth, y:bounds.height)
            path.move(to: start)
            path.addLine(to: end)
        }

        for index in 1...Int(gridHeightMultiple) - 1 {
            let start = CGPoint(x: 0, y: CGFloat(index) * gridHeight)
            let end = CGPoint(x: bounds.width, y: CGFloat(index) * gridHeight)
            path.move(to: start)
            path.addLine(to: end)
        }

        //Close the path.
        path.close()

    }

    override func draw(_ rect: CGRect)
    {
        drawGrid()

        // Specify a border (stroke) color.
        UIColor.purple.setStroke()
        path.stroke()
    }
}

Answer 2

如果您想在初始化视图时进行绘制逻辑，但是实际上您想稍后绘制线条，即发生某些特殊事件时。贝娄类有两种方法drawGridWithStoreColor和removeGrid，这将帮助您在需要时绘制网格，并在需要时删除网格。

class GridView: UIView
{
    private var path = UIBezierPath()
    var gridLayer: CAShapeLayer?

    fileprivate var gridWidthMultiple: CGFloat
    {
        return 10
    }
    fileprivate var gridHeightMultiple : CGFloat
    {
        return 20
    }

    fileprivate var gridWidth: CGFloat
    {
        return bounds.width/CGFloat(gridWidthMultiple)
    }

    fileprivate var gridHeight: CGFloat
    {
        return bounds.height/CGFloat(gridHeightMultiple)
    }

    fileprivate var gridCenter: CGPoint {
        return CGPoint(x: bounds.midX, y: bounds.midY)
    }

    fileprivate func drawGrid()
    {
        path = UIBezierPath()
        path.lineWidth = 5.0

        for index in 1...Int(gridWidthMultiple) - 1
        {
            let start = CGPoint(x: CGFloat(index) * gridWidth, y: 0)
            let end = CGPoint(x: CGFloat(index) * gridWidth, y:bounds.height)
            path.move(to: start)
            path.addLine(to: end)
        }


    }

    //Call this method with your stroke color when you want to draw this grid
    func drawGridWithColor(borderColor: UIColor) {
        //Close the path.
        path.close()
        if gridLayer == nil {
            gridLayer = CAShapeLayer()
            gridLayer?.lineWidth = 5.0;
            gridLayer?.path = path.cgPath
            gridLayer?.strokeColor = borderColor.cgColor

            self.layer.addSublayer(gridLayer!)
            //Above line will add this grid at the very top of this view.



            // if you want to add this grid below some layer/object you can use method
            //self.layer.insertSublayer(gridLayer, at: 0)
            //Give the index number to this method so that it can place this grid at the index

        }else {
            gridLayer?.strokeColor = borderColor.cgColor
        }
    }

    func removeGrid() {
        guard let gLayer = gridLayer else {return}
        gLayer.removeFromSuperlayer()
    }

    override func draw(_ rect: CGRect)
    {
        drawGrid()
    }
}