Drawing selection box (rubberbanding, marching ants) in Cocoa, ObjectiveC

Question

I\'ve currently implemented a simple selection box using mouse events and redrawing a rectangle on mouse drag. Here\'s my code:

-(void)drawRect:(NSRect)dirty         


        

Answer 1

swift 3 version:

import Cocoa
import QuartzCore

class myView: NSView {

    //MARK:Properties
    var startPoint : NSPoint!
    var shapeLayer : CAShapeLayer!

    override func draw(_ dirtyRect: NSRect) {
        super.draw(dirtyRect)

        // Drawing code here.
    }


    override func mouseDown(with event: NSEvent) {

        self.startPoint = self.convert(event.locationInWindow, from: nil)

        shapeLayer = CAShapeLayer()
        shapeLayer.lineWidth = 1.0
        shapeLayer.fillColor = NSColor.clear.cgColor
        shapeLayer.strokeColor = NSColor.black.cgColor
        shapeLayer.lineDashPattern = [10,5]
        self.layer?.addSublayer(shapeLayer)

        var dashAnimation = CABasicAnimation()
        dashAnimation = CABasicAnimation(keyPath: "lineDashPhase")
        dashAnimation.duration = 0.75
        dashAnimation.fromValue = 0.0
        dashAnimation.toValue = 15.0
        dashAnimation.repeatCount = .infinity
        shapeLayer.add(dashAnimation, forKey: "linePhase")




    }

    override func mouseDragged(with event: NSEvent) {

        let point : NSPoint = self.convert(event.locationInWindow, from: nil)
        let path = CGMutablePath()
        path.move(to: self.startPoint)
        path.addLine(to: NSPoint(x: self.startPoint.x, y: point.y))
        path.addLine(to: point)
        path.addLine(to: NSPoint(x:point.x,y:self.startPoint.y))
        path.closeSubpath()
        self.shapeLayer.path = path
    }

    override func mouseUp(with event: NSEvent) {
        self.shapeLayer.removeFromSuperlayer()
        self.shapeLayer = nil
    }


}