drawing dashed line using CALayer

Question

I was able to draw a dashed box, using the following code:

CAShapeLayer *shapeLayer = [CAShapeLayer layer];
CGRect shapeRect = CGRectMake(0.0f, 0.0f, 200.0f,         


        

Answer 1

Below is the code snippet to draw a Dashed line in UIView (Xamarin iOS)

Note: separatorView is my UIView which i need to show as Dashed

 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);
 }

Answer 2

Swift 2.2

dropping this in here to save others time..

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)
    }
}

Answer 3

See:

https://developer.apple.com/library/mac/documentation/graphicsimaging/Reference/CGContext/Reference/reference.html#//apple_ref/c/func/CGContextSetLineDash

CGFloat dashLengths[] = { 10, 5 };
CGContextSetLineDash(context, 0, dashLengths, 2);

Answer 4

Got it working in Objective C with the simplified code as below

   //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];

Answer 5

Lines are drawn by first moving the path to a starting point of the line, then adding a line segment to a point:

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

For drawing dashed line, You need to use 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];

Answer 6

Try this code, it works for me,

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)
    }
}