How to properly place SCNNode on top of the QR Code? - swift

Question

I want to detect QR codes in the vertical plane and place a node on top of the detected QR. For QR detection, I used Vision framework and Arkit to place the nodes as below code. Whenever placing the node, it is not attached to the QR code and placed somewhere else.
Could someone help to figure out what I have done wrong?
class ViewController: UIViewController, ARSCNViewDelegate,ARSessionDelegate{
#IBOutlet var sceneView: ARSCNView!
var qrRequests = [VNRequest]()
var detectedDataAnchor: ARAnchor?
var processing = false
let configuration = ARWorldTrackingConfiguration()
override func viewDidLoad() {
super.viewDidLoad()
self.sceneView.delegate = self
self.sceneView.session.delegate = self
self.sceneView.session.run(configuration)
startQrCodeDetection()
}
func startQrCodeDetection() {
let request = VNDetectBarcodesRequest(completionHandler: self.requestHandler)
self.qrRequests = [request]
}
public func session(_ session: ARSession, didUpdate frame: ARFrame) {
DispatchQueue.global(qos: .userInitiated).async {
do {
if self.processing {
return
}
self.processing = true
let imageRequestHandler = VNImageRequestHandler(cvPixelBuffer: frame.capturedImage,
options: [:])
try imageRequestHandler.perform(self.qrRequests)
} catch {
}
}
}
func requestHandler(request: VNRequest, error: Error?) {
if let results = request.results, let result = results.first as? VNBarcodeObservation {
guard let payload = result.payloadStringValue else {return}
var rect = result.boundingBox
let center = CGPoint(x: rect.midX, y: rect.midY)
DispatchQueue.main.async {
self.hitTestQrCode(center: center)
self.processing = false
}
} else {
self.processing = false
}
}
func hitTestQrCode(center: CGPoint) {
print("Hit Test")
if let hitTestResults = self.sceneView?.hitTest(center, types: [.featurePoint, .existingPlaneUsingExtent] ),
let hitTestResult = hitTestResults.first {
if let detectedDataAnchor = self.detectedDataAnchor,
let node = self.sceneView.node(for: detectedDataAnchor) {
node.transform = SCNMatrix4(hitTestResult.worldTransform)
} else {
self.detectedDataAnchor = ARAnchor(transform: hitTestResult.worldTransform)
self.sceneView.session.add(anchor: self.detectedDataAnchor!)
}
}
}
func renderer(_ renderer: SCNSceneRenderer, nodeFor anchor: ARAnchor) -> SCNNode? {
if self.detectedDataAnchor?.identifier == anchor.identifier {
let sphere = SCNSphere(radius: 0.02)
sphere.firstMaterial?.diffuse.contents = UIColor.red
let sphereNode = SCNNode(geometry: sphere)
sphereNode.transform = SCNMatrix4(anchor.transform)
return sphereNode
}
return nil
}
}