SCNNode is not showing up - swift

Question

I'm new in Swift and ARKit. For some reason the SCNNode node I'm trying to display is not showing up. I'm working with SwiftUI. I defined in the next code block the function addNode that should render the node.
import Foundation
import ARKit
import SwiftUI
// MARK: - ARViewIndicator
struct ARViewIndicator: UIViewControllerRepresentable {
typealias UIViewControllerType = ARView
func makeUIViewController(context: Context) -> ARView {
return ARView()
}
func updateUIViewController(_ uiViewController:
ARViewIndicator.UIViewControllerType, context:
UIViewControllerRepresentableContext<ARViewIndicator>) { }
}
class ARView: UIViewController, ARSCNViewDelegate {
var arView: ARSCNView {
return self.view as! ARSCNView
}
override func loadView() {
self.view = ARSCNView(frame: .zero)
}
override func viewDidLoad() {
super.viewDidLoad()
arView.delegate = self
arView.scene = SCNScene()
}
// MARK: - Functions for standard AR view handling
override func viewDidAppear(_ animated: Bool) {
super.viewDidAppear(animated)
}
override func viewDidLayoutSubviews() {
super.viewDidLayoutSubviews()
}
override func viewWillAppear(_ animated: Bool) {
super.viewWillAppear(animated)
let configuration = ARWorldTrackingConfiguration()
arView.debugOptions = [.showFeaturePoints,
.showWorldOrigin]
arView.session.run(configuration)
arView.delegate = self
}
override func viewWillDisappear(_ animated: Bool) {
super.viewWillDisappear(animated)
arView.session.pause()
}
func addNode(){
let node = SCNNode()
node.geometry = SCNBox(width: 0.1,
height: 0.1,
length: 0.1,
chamferRadius: 0)
node.geometry?.firstMaterial?.diffuse.contents = UIColor.blue
node.position = SCNVector3(0,0,0.3)
arView.scene.rootNode.addChildNode(node)
arView.delegate = self
print(123)
}
// MARK: - ARSCNViewDelegate
func sessionWasInterrupted(_ session: ARSession) {}
func sessionInterruptionEnded(_ session: ARSession) {}
func session(_ session: ARSession, didFailWithError error: Error)
{}
func session(_ session: ARSession, cameraDidChangeTrackingState
camera: ARCamera) {}
}
... and that function is invoked when clicking the button "HOME"
import SwiftUI
import ARKit
// MARK: - NavigationIndicator
struct NavigationIndicator: UIViewControllerRepresentable {
typealias UIViewControllerType = ARView
func makeUIViewController(context: Context) -> ARView {
return ARView()
}
func updateUIViewController(_ uiViewController:
NavigationIndicator.UIViewControllerType, context:
UIViewControllerRepresentableContext<NavigationIndicator>) { }
}
struct ContentView: View {
#State var page = "Home"
var body: some View {
VStack {
ZStack {
NavigationIndicator()
VStack {
Spacer()
HStack {
Button("Home") {
let ar = ARView();
ar.addNode()
}.padding()
.background(RoundedRectangle(cornerRadius: 10)
.foregroundColor(Color.white).opacity(0.7))
Spacer()
}
}
}
}
}
}
struct ContentView_Previews: PreviewProvider {
static var previews: some View {
ContentView()
}
}
Do you know why it's not showing up ?
Thanks in advance !

Answer 1

Use this approach for SceneKitView:
import SwiftUI
import ARKit
struct SceneKitView: UIViewRepresentable {
let arView = ARSCNView(frame: .zero)
#Binding var pressed: Bool
#Binding var node: SCNNode
func makeCoordinator() -> Coordinator {
Coordinator(self)
}
final class Coordinator: NSObject, ARSCNViewDelegate {
var control: SceneKitView
init(_ control: SceneKitView) {
self.control = control
}
func renderer(_ renderer: SCNSceneRenderer,
updateAtTime time: TimeInterval) {
if control.pressed {
self.control.node = self.addCube()
self.control.arView.scene.rootNode.addChildNode(control.node)
}
}
fileprivate func addCube() -> SCNNode {
control.node.geometry = SCNBox(width: 0.25,
height: 0.25,
length: 0.25,
chamferRadius: 0.01)
control.node.geometry?.firstMaterial?.diffuse.contents = UIColor.blue
control.node.geometry?.firstMaterial?.lightingModel = .phong
control.node.position = SCNVector3(0, 0,-2)
return control.node
}
}
func makeUIView(context: Context) -> ARSCNView {
arView.scene = SCNScene()
arView.delegate = context.coordinator
arView.autoenablesDefaultLighting = true
arView.debugOptions = .showFeaturePoints
// arView.allowsCameraControl = true
let config = ARWorldTrackingConfiguration()
arView.session.run(config)
return arView
}
func updateUIView(_ uiView: ARSCNView,
context: Context) { }
}
Then use this code for ContentView.
struct ContentView: View {
#State var pressed: Bool = false
#State var node = SCNNode()
var body: some View {
ZStack {
SceneKitView(pressed: $pressed, node: $node)
VStack {
Spacer()
HStack {
Button("Blue Cube") {
pressed.toggle()
}.padding()
.foregroundColor(.red)
Spacer()
}
}
}
}
}
P.S.
However, a strange issue occurs with ARSCNView in Simulator – after pressing a button a SCNBox appears only after tapping a screen with .allowsCameraControl = true.