Snippet for handlePan within the ARSupportAudienceViewController

handlePan+Snippet.swift

@IBAction func handlePan(_ gestureRecognizer: UIPanGestureRecognizer) {

        // TODO: send touch started event
        
        // keep track of points captured during pan gesture
        if self.sessionIsActive && (gestureRecognizer.state == .began || gestureRecognizer.state == .changed) {
            let translation = gestureRecognizer.translation(in: self.view)
            // calculate touch movement relative to the superview
            guard let touchStart = self.touchStart else { return } // ignore accidental finger drags
            let pixelTranslation = CGPoint(x: touchStart.x + translation.x, y: touchStart.y + translation.y)
            
            // normalize the touch point to use view center as the reference point
            let translationFromCenter = CGPoint(x: pixelTranslation.x - (0.5 * self.view.frame.width), y: pixelTranslation.y - (0.5 * self.view.frame.height))
            
            self.touchPoints.append(pixelTranslation)
            
            // TODO: Send captured points
            
            DispatchQueue.main.async {
                // draw user touches to the DrawView
                guard let drawView = self.drawingView else { return }
                guard let lineColor: UIColor = self.lineColor else { return }
                let layer = CAShapeLayer()
                layer.path = UIBezierPath(roundedRect: CGRect(x:  pixelTranslation.x, y: pixelTranslation.y, width: 25, height: 25), cornerRadius: 50).cgPath
                layer.fillColor = lineColor.cgColor
                drawView.layer.addSublayer(layer)
            }
            
            if debug {
                print(translationFromCenter)
                print(pixelTranslation)
            }
        }
        
        if gestureRecognizer.state == .ended {
            // TODO: send message to remote user that touches have ended

            // clear list of points
            if let touchPointsList = self.touchPoints {
                self.touchStart = nil // clear starting point
                if debug {
                    print(touchPointsList)
                }
            }
        }
    }