绘制虚线(不是虚线！)线，2017 年使用 IBDesignable [英] Draw dotted (not dashed!) line, with IBDesignable in 2017

问题描述

使用 UIKit 绘制虚线很容易.所以:

It's easy to draw a dashed line with UIKit. So:

CGFloat dashes[] = {4, 2};
[path setLineDash:dashes count:2 phase:0];
[path stroke];

有没有办法画出真正的虚线?

Is there any way way to draw a genuine dotted line?

推荐答案

将线帽样式设置为圆形并将开启"长度设置为一个很小的数字.

Set the line cap style to round and set the "on" length to a tiny number.

Swift 游乐场示例:

Swift playground example:

import UIKit
import PlaygroundSupport

let path = UIBezierPath()
path.move(to: CGPoint(x:10,y:10))
path.addLine(to: CGPoint(x:290,y:10))
path.lineWidth = 8

let dashes: [CGFloat] = [0.001, path.lineWidth * 2]
path.setLineDash(dashes, count: dashes.count, phase: 0)
path.lineCapStyle = CGLineCap.round

UIGraphicsBeginImageContextWithOptions(CGSize(width:300, height:20), false, 2)

UIColor.white.setFill()
UIGraphicsGetCurrentContext()!.fill(.infinite)

UIColor.black.setStroke()
path.stroke()

let image = UIGraphicsGetImageFromCurrentImageContext()
let view = UIImageView(image: image)
PlaygroundPage.current.liveView = view

UIGraphicsEndImageContext()

结果:

对于objective-C，使用与问题中相同的示例类，只需添加

For objective-C, using the same example class as in the question, simply add

CGContextSetLineCap(cx, kCGLineCapRound);

在调用 CGContextStrokePath 之前，更改 ra 数组值以匹配我的 Swift 代码.

before the call to CGContextStrokePath, and change the ra array values to match my Swift code.

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