Iphone 使用CALayer绘制虚线

我能够使用以下代码绘制一个虚线框：

CAShapeLayer *shapeLayer = [CAShapeLayer layer];
CGRect shapeRect = CGRectMake(0.0f, 0.0f, 200.0f, 100.0f);
[shapeLayer setBounds:shapeRect];
[shapeLayer setPosition:CGPointMake(self.coreImageView_.frameX, self.coreImageView_.frameBottom - self.coreImageView_.frameHeight/2)];
[shapeLayer setFillColor:[[UIColor clearColor] CGColor]];
[shapeLayer setStrokeColor:[[UIColor whiteColor] CGColor]];
[shapeLayer setLineWidth:2.0f];
[shapeLayer setLineJoin:kCALineJoinRound];
[shapeLayer setLineDashPattern:
[NSArray arrayWithObjects:[NSNumber numberWithInt:5],
[NSNumber numberWithInt:5],
  nil]];

---

现在，如果我只想从点X到点B绘制一条虚线，我应该如何修改此代码？

首先将路径移动到线的起点，然后将线段添加到点，以绘制线：

CGContextBeginPath(context);
CGContextMoveToPoint(context, 10.5f, 10.5f);
CGContextAddLineToPoint(context, 20.5f, 20.5f);
CGContextClosePath(context);
CGContextDrawPath(context, kCGPathFillStroke);

对于绘制虚线，需要使用CAShapeLayer

CAShapeLayer *shapeLayer = [CAShapeLayer layer];
[shapeLayer setBounds:self.bounds];
[shapeLayer setPosition:self.center];
[shapeLayer setFillColor:[[UIColor clearColor] CGColor]];
[shapeLayer setStrokeColor:[[UIColor blackColor] CGColor]];
[shapeLayer setLineWidth:3.0f];
[shapeLayer setLineJoin:kCALineJoinRound];
[shapeLayer setLineDashPattern:
 [NSArray arrayWithObjects:[NSNumber numberWithInt:10],
  [NSNumber numberWithInt:5],nil]];

// Setup the path
CGMutablePathRef path = CGPathCreateMutable();
CGPathMoveToPoint(path, NULL, 10, 10);
CGPathAddLineToPoint(path, NULL, 100,100);

[shapeLayer setPath:path];
CGPathRelease(path);

[[self layer] addSublayer:shapeLayer];

见：

---

Swift 2.2

把这个放在这里是为了节省别人的时间

extension UIView {
    func addDashedLine(color: UIColor = UIColor.lightGrayColor()) {
        layer.sublayers?.filter({ $0.name == "DashedTopLine" }).map({ $0.removeFromSuperlayer() })
        self.backgroundColor = UIColor.clearColor()
        let cgColor = color.CGColor

        let shapeLayer: CAShapeLayer = CAShapeLayer()
        let frameSize = self.frame.size
        let shapeRect = CGRect(x: 0, y: 0, width: frameSize.width, height: frameSize.height)

        shapeLayer.name = "DashedTopLine"
        shapeLayer.bounds = shapeRect
        shapeLayer.position = CGPoint(x: frameSize.width / 2, y: frameSize.height / 2)
        shapeLayer.fillColor = UIColor.clearColor().CGColor
        shapeLayer.strokeColor = cgColor
        shapeLayer.lineWidth = 1
        shapeLayer.lineJoin = kCALineJoinRound
        shapeLayer.lineDashPattern = [4, 4]

        let path: CGMutablePathRef = CGPathCreateMutable()
        CGPathMoveToPoint(path, nil, 0, 0)
        CGPathAddLineToPoint(path, nil, self.frame.width, 0)
        shapeLayer.path = path

        self.layer.addSublayer(shapeLayer)
    }
}

快捷、更紧凑：

func addDashedLine(fromPoint start: CGPoint, toPoint end:CGPoint) {
    let line = CAShapeLayer()
    let linePath = UIBezierPath()
    linePath.moveToPoint(start)
    linePath.addLineToPoint(end)
    line.path = linePath.CGPath
    line.strokeColor = UIColor.redColor().CGColor
    line.lineWidth = 1
    line.lineJoin = kCALineJoinRound
    line.lineDashPattern = [4, 4]
    self.layer.addSublayer(line)
}

---

试试这个代码，它对我有用

Swift 3.0

extension UIView {
    func addDashedLine(strokeColor: UIColor, lineWidth: CGFloat) {

        backgroundColor = .clear

        let shapeLayer = CAShapeLayer()
        shapeLayer.name = "DashedTopLine"
        shapeLayer.bounds = bounds
        shapeLayer.position = CGPoint(x: frame.width / 2, y: frame.height / 2)
        shapeLayer.fillColor = UIColor.clear.cgColor
        shapeLayer.strokeColor = strokeColor.cgColor
        shapeLayer.lineWidth = lineWidth
        shapeLayer.lineJoin = kCALineJoinRound
        shapeLayer.lineDashPattern = [4, 4]

        let path = CGMutablePath()
        path.move(to: CGPoint.zero)
        path.addLine(to: CGPoint(x: frame.width, y: 0))
        shapeLayer.path = path

        layer.addSublayer(shapeLayer)
    }
}

---

让它在目标C中工作，简化代码如下

   //Dashed line for road
    CAShapeLayer *dashedLine = [CAShapeLayer layer];
    [dashedLine setFrame:CGRectMake(0, 342, 100 , 100)];

    // Setup the path
    CGMutablePathRef thePath = CGPathCreateMutable();
    CGPathMoveToPoint(thePath, NULL, 0, 10);
    CGPathAddLineToPoint(thePath, NULL, screenSize.width,10);
    dashedLine.path = thePath;
    CGPathRelease(thePath);

    [dashedLine setLineDashPattern: [NSArray arrayWithObjects:[NSNumber numberWithFloat:15], nil]];
    dashedLine.lineWidth = 1.0f;
    dashedLine.strokeColor =  [[UIColor redcolor] CGColor]];

    [self.view.layer addSublayer:dashedLine];

---

下面是在UIView（Xamarin iOS）中绘制虚线的代码片段

注: 分隔视图是我需要以虚线显示的UIView

 public void ShowDottedLine()
 {
      var dashedLayer = new CAShapeLayer();
      var frameSize = separatorView.Frame.Size;
      var shapeRect = new CGRect(0, 0, frameSize.Width, frameSize.Height);
      dashedLayer.Bounds = shapeRect;
      dashedLayer.Position = new CGPoint(frameSize.Width / 2, frameSize.Height / 2);
      dashedLayer.FillColor = UIColor.Clear.CGColor;
      dashedLayer.StrokeColor = ColorUtils.ColorWithHex(ColorConstants.DarkBlue).CGColor;
      dashedLayer.LineWidth = 2;
      dashedLayer.LineJoin = CAShapeLayer.JoinRound;
      NSNumber[] patternArray = {5,5};
      dashedLayer.LineDashPattern = Array;
      var path = new CGPath();
      path.MoveToPoint(CGPoint.Empty);
      path.AddLineToPoint(new CGPoint(frameSize.Width, 0));
      dashedLayer.Path = path;
      separatorView.Layer.AddSublayer(dashedLayer);
 }

---

你说的X点和B点是什么意思？它们是矩形上的点，或者它们在屏幕上的任何位置都只有2个点？可能是重复的我用头在墙上撞了好几个小时，试图用CGContext做到这一点。非常感谢！感谢您提供这段代码片段，它可能会提供一些即时帮助。一个恰当的解释将通过说明为什么这是一个很好的解决问题的方法来体现它的教育价值，并将使它对未来有类似但不完全相同问题的读者更有用。请编辑您的答案以添加解释，并说明适用的限制和假设。

CAShapeLayer *shaplayer = [CAShapeLayer layer];
    shaplayer.frame = CGRectMake(100, 100, 100, 100);
    [self.view.layer addSublayer:shaplayer];
    UIBezierPath *uipath = [UIBezierPath bezierPath];
    [uipath moveToPoint:CGPointMake(50, 200)];
    [uipath addLineToPoint:CGPointMake(250, 200)];
    shaplayer.path = uipath.CGPath;
    shaplayer.strokeColor = [UIColor redColor].CGColor;
    shaplayer.lineDashPattern = @[@4];

 public void ShowDottedLine()
 {
      var dashedLayer = new CAShapeLayer();
      var frameSize = separatorView.Frame.Size;
      var shapeRect = new CGRect(0, 0, frameSize.Width, frameSize.Height);
      dashedLayer.Bounds = shapeRect;
      dashedLayer.Position = new CGPoint(frameSize.Width / 2, frameSize.Height / 2);
      dashedLayer.FillColor = UIColor.Clear.CGColor;
      dashedLayer.StrokeColor = ColorUtils.ColorWithHex(ColorConstants.DarkBlue).CGColor;
      dashedLayer.LineWidth = 2;
      dashedLayer.LineJoin = CAShapeLayer.JoinRound;
      NSNumber[] patternArray = {5,5};
      dashedLayer.LineDashPattern = Array;
      var path = new CGPath();
      path.MoveToPoint(CGPoint.Empty);
      path.AddLineToPoint(new CGPoint(frameSize.Width, 0));
      dashedLayer.Path = path;
      separatorView.Layer.AddSublayer(dashedLayer);
 }