Method `enumerateChildNodes` is not finding nodes

Question

I'm developing an ARKit app that has 2 buttons: "Play" and "Reset". When I click on Play, a pyramid node is displayed. When I click on Reset, all pyramid nodes should be deleted from the scene:

Another requirement is that I want to disable the Play button when I click on it.

Next is my contentView code:

import ARKit

struct ContentView: View {
    
    @State var node = SCNNode()
    @State var play: Bool = false
    @State var reset: Bool = false
    @State var isDisabled: Bool = false
    @State var showBanner:Bool = true
    
    var body: some View {
        ZStack {
            SceneKitView(node: $node, play: $play, reset: $reset, isDisabled: $isDisabled)
            VStack {
                Spacer()
                HStack {
                    Button(action: {
                        play = true
                    }) {
                        Image("Play")
                    }.padding()
                    .disabled(isDisabled) /// <<<<< THIS DISABLES THE BUTTON

                    Spacer()
                    
                    Button(action: {
                        play = false                        
                        reset = true
                    }) {
                        Image("Reset")
                    }.padding()
                }
            }
        }
    }
    
    
}

struct ContentView_Previews: PreviewProvider {
    static var previews: some View {
        ContentView()
    }
}

In order to disable the Play button, I'm using a .disabled and the Boolean isDisabled.

My code changes the value of isDisabled to TRUE in a Coordinator :

import ARKit
import SwiftUI

struct SceneKitView: UIViewRepresentable {
    let arView = ARSCNView(frame: .zero)
    let config = ARWorldTrackingConfiguration()
    @Binding var node: SCNNode
    @Binding var play: Bool
    @Binding var reset: Bool
    @Binding var isDisabled: Bool
    
    
    func makeCoordinator() -> Coordinator {
        Coordinator(self)
    }
    
    final class Coordinator: NSObject, ARSCNViewDelegate {
        var control: SceneKitView
        init(_ control: SceneKitView) {
            self.control = control
        }
        func renderer(_ renderer: SCNSceneRenderer, willRenderScene scene: SCNScene, atTime time: TimeInterval) {
            DispatchQueue.main.async {
                if self.control.play {
                    self.control.addNode()
                    self.control.play = false
                    self.control.isDisabled = true // HERE I UPDATE THE VALUE !!!!!!!!
                    self.control.reset = false
                }else{
                }
            }
        }
    }
    
    func removeNode(){
        self.arView.scene.rootNode.enumerateChildNodes { (node, _) in
            print("existing nodes = \(node)")
            node.removeFromParentNode()
        }
    }
    
    func updateUIView(_ uiView: ARSCNView,
     context: Context) {
        if self.reset {
            self.removeNode()
            print("game reseted")
        }
    }
    
    func makeUIView(context: Context) -> ARSCNView {
        arView.scene = SCNScene()
        arView.delegate = context.coordinator
        arView.autoenablesDefaultLighting = true
        //arView.debugOptions = [ARSCNDebugOptions.showFeaturePoints, ARSCNDebugOptions.showWorldOrigin]
        arView.showsStatistics = true
        arView.session.run(self.config)
        return arView
    }
    
    func addNode(){
        let pyramid = SCNNode(geometry: SCNPyramid(width: 0.1, height: 0.1, length: 0.1))
        pyramid.geometry?.firstMaterial?.diffuse.contents = UIColor.red
        pyramid.geometry?.firstMaterial?.specular.contents = UIColor.white
        pyramid.position = SCNVector3(0,0,-0.5)
        self.arView.scene.rootNode.addChildNode(pyramid)
    }
    
}

Problem: When the app is running and I click on RESET, the method removeNode is invoked and this method uses enumerateChildNodes to find the nodes and delete them using removeFromParentNode but the pyramid node is not removed ! :(

The crazy thing (for me) is that if I don't change the value of isDisabled in the Coordinator, i.e. I comment that line, removeNode works, and the node is removed !!!!!

Any comment, suggestion is welcome :)

Answer 1

This solves the issue:

func updateUIView(_ uiView: ARSCNView, context: Context) {
    if self.reset {
        DispatchQueue.main.async {
            context.coordinator.control.removeNode()
            context.coordinator.control.isDisabled = false
        }
        print("Game Reset")
    }
}