iOS CALayer tap recognizer

Question

I have a line like this:

Which is drawn on a CAShapeLayer using the following code:

class LineView: UIView {

    let rwPath = UIBezierPath()
    let rwLayer = CAShapeLayer()
    let rwColor = UIColor(red: 11/255.0, green: 86/255.0, blue: 14/255.0, alpha: 1.0)

    func setData() {
        rwPath.move(to: CGPoint(x: 50.0, y: 50.0))
        for i in 1...200 {
            rwPath.addLine(to: CGPoint(x: i + 50, y: i + 50))
        }

        setUpRWLayer()
        layer.addSublayer(rwLayer)
    }

    private func setUpRWLayer() {
        rwLayer.path = rwPath.cgPath
        rwLayer.fillColor = nil
        rwLayer.lineCap = .butt
        rwLayer.lineDashPattern = nil
        rwLayer.lineDashPhase = 0.0
        rwLayer.lineJoin = .miter
        rwLayer.lineWidth = 3.0
        rwLayer.miterLimit = 10.0
        rwLayer.strokeColor = rwColor.cgColor
    }
}

I've been trying for a while to detect a tap on that line. I've tried using UITapGestureRecognizer and overriding touchesBegin:withEvent func, but nothing seems to work so I've come to ask here.

Hit test code:

override func touchesBegan(_ touches: Set<UITouch>, with event: UIEvent?) {
    let point = touches.first?.location(in: self)

    if let hitLayer = self.layer.hitTest(point!) as? CAShapeLayer {
        if (hitLayer.path?.contains(point!))! {
            print("Touched")
        }
    }
}

Have you tried the solutions listed here? https://stackoverflow.com/q/29773165/3151675 Make sure user interaction is enabled. — Tamás Sengel, Dec 27 '19 at 10:17
Yes I have tried, user interaction is enabled. That one didn't work. I can print out the CGPoint which I click but when I try to do a hitTest it always fails, no matter where I clicked. — Duško Mirković, Dec 27 '19 at 10:22
Please include the hit testing code in the question as well. — Tamás Sengel, Dec 27 '19 at 10:30

score 1 · Accepted Answer · answered Dec 27 '19 at 11:11

You need to create outline for it as it will work accurately for click event on CAShape layer

Try this code and let me know if you face any issue

override func touchesBegan(_ touches: Set<UITouch>, with event: UIEvent?) {
    let touch = touches.first

    guard let point = touch?.location(in: self.view) else { return }
    guard let sublayers = self.view.layer.sublayers else { return }
    var caShapelayers : [CAShapeLayer] = []
    for layer in sublayers {
        if layer is CAShapeLayer{
            caShapelayers.append(layer as! CAShapeLayer)
        }
    }

    for layer in caShapelayers {
        if let path = layer.path{
            let outline = path.copy(strokingWithWidth: 13, lineCap: .square, lineJoin: .round, miterLimit: 0)

            let iscontain = outline.contains(point)
            if iscontain  {
                //    print(layer)
                Singleton.sharedSingleton.showAlert(controller: self, message: "You want to delete this link?", title: "Are you sure?") { (buttonPressed) in
                    if (buttonPressed == "YES"){
                        layer.removeFromSuperlayer()
                    }
                }

            }
        }

    }
}

iOS CALayer tap recognizer

1 Answers1