Detecting a tap on a CAShapeLayer in Swift?

Question

I'm quite new to iOS Development (so please forgive my ineptitude - I've looked everywhere!), and was looking to find a way to detect a tap on a CAShapeLayer. So far, I've come across hitTest. Is hitTest the best method, and if so how is it used in Swift especially with CAShapeLayers? Also, if I had numerous CAShapeLayers, how would I use the hitTest method to refer to them individually?

This is how I created the CAShapeLayer:

    let newBounds = CGRect(x: 0, y: 0, width: 200, height: 200)
    let newShape = CAShapeLayer()
    newShape.bounds = newBounds
    newShape.position = view.center
    newShape.cornerRadius = newBounds.width / 2
    newShape.path = UIBezierPath(ovalInRect: newShape.bounds).CGPath

    newShape.lineWidth = 42
    newShape.strokeColor = UIColor(red: 222/255.0, green: 171/255.0, blue: 66/255.0, alpha: 1.0).CGColor
    newShape.fillColor = UIColor.clearColor().CGColor

    newShape.strokeStart = 0.2
    newShape.strokeEnd = 0.4

    view.layer.addSublayer(newShape)

Meridel

Answer 1

Heres imo the best way to do what you want to achieve:

// First add the shapelayer
let layer = CAShapeLayer()
layer.anchorPoint = CGPointZero
layer.path = UIBezierPath(ovalInRect: CGRect(x: 0, y: 0, width: 100, height: 200)).CGPath
layer.bounds = CGPathGetBoundingBox(layer.path) // IMPORTANT, without this hitTest wont work
layer.fillColor = UIColor.redColor().CGColor
self.view.layer.addSublayer(layer)


// Check for touches
override func touchesBegan(touches: NSSet, withEvent event: UIEvent) {
    let point = touches.anyObject()!.locationInView(self.view) // Where you pressed

    if let layer = self.view.layer.hitTest(point) as? CAShapeLayer { // If you hit a layer and if its a Shapelayer
        if CGPathContainsPoint(layer.path, nil, point, false) { // Optional, if you are inside its content path
            println("Hit shapeLayer") // Do something
        }
    }
}

Sundog

I tried your code but nothing is printing to the console when I tap on the CAShapeLayer for some reason. – Meridel

Show me how you create that shapelayer – Sundog

I've got it to work, thanks! Also, if I had numerous CAShapeLayers, how would I use that hitTest method to refer to them individually? – Meridel

You could subclass and give it a property called tag or identifier amd then check för that property. – Sundog

Or you can make them a property in your view or viewcontroller and check for eatch one. – Sundog

CAShapeLayer not detect can you help me? – Levorotation

Answer 2

Swift 4 & 5

My UIImageView has multiple embedded CAShapeLayer objects. Here is how I was able to detect taps on them. Referenced from this tutorial.

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

    guard let point = touch?.location(in: imageView) else { return }
    guard let sublayers = imageView.layer.sublayers as? [CAShapeLayer] else { return }

    for layer in sublayers {
        if let path = layer.path, path.contains(point) {
            print(layer)
        }
    }
}

Foretime

Answer 3

I used Arbitur's code and i had some errors. Here is a code i had with no errors. For swift 3.2 / 4.0

override func viewDidLoad() {
    super.viewDidLoad()

    let layer = CAShapeLayer()
    layer.anchorPoint = CGPoint.zero
    layer.path = UIBezierPath.init(ovalIn: CGRect(x: 0, y: 0, width: 100, height: 200)).cgPath
    layer.bounds = (layer.path?.boundingBox)! // IMPORTANT, without this hitTest wont work
    layer.fillColor = UIColor.red.cgColor
    self.view.layer.addSublayer(layer)

}
    // Check for touches

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

    if let layer = self.view.layer.hitTest(point!) as? CAShapeLayer { // If you hit a layer and if its a Shapelayer
        if (layer.path?.contains(point!))! { // Optional, if you are inside its content path
            print("Hit shapeLayer") // Do something
        }
    }
}

Yod

Answer 4

Use following code for get touch of CAShapeLayer.

- (void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event
{
    for (UITouch *touch in touches) {
        CGPoint touchLocation = [touch locationInView:self.view];
        for (id sublayer in self.view.layer.sublayers) {
            BOOL touchInLayer = NO;
            if ([sublayer isKindOfClass:[CAShapeLayer class]]) {
                CAShapeLayer *shapeLayer = sublayer;
                if (CGPathContainsPoint(shapeLayer.path, 0, touchLocation, YES)) {
                    // Here your code for do any opration.
                    touchInLayer = YES;
                }
            } else {
                CALayer *layer = sublayer;
                if (CGRectContainsPoint(layer.frame, touchLocation)) {
                    // Touch is in this rectangular layer
                    touchInLayer = YES;
                }
            }
        }
    }
}

Marsipobranch

Thanks. Do you know if I could get this code in Swift? – Meridel

I strongly recommend hitTest over this. – Sundog

But we can't directly detect the event on CAShapeLayer.- (void)tap:(UITapGestureRecognizer*)recognizer { //I've had the tapGestureRecognizer to rainbowView (that is an UIView) in viewDidLoad CGLayer* tappedLayer = [rainbowView.layer.presentationlayer hitTest:[recognizer locationInView:rainbowView]; if (tappedLayer == purpleLayer) //for example NSLog(@"PURPLE!"); } also not work – Marsipobranch