How can I let the plane collide with an object in RealityKit - swift

Question

I have a ball and a plane (floor) in realityKit.
The ball falls and has to collide on the plane. But the ball is falling through the plane. When the ball hits the plane i want a print statement "OCCURED" but this is also not happening.
My code:
struct ARViewContainer: UIViewRepresentable {
let arView = ARView(frame: .zero)
func makeUIView(context: Context) -> ARView {
var subscriptions: [Cancellable] = []
let anchor = AnchorEntity()
//generate a plane
let planeModel = ModelEntity(mesh: .generatePlane(width: 2.0,
depth: 2.0))
as (Entity & HasCollision)
planeModel.position = [0,-10,-1.5]
planeModel.generateCollisionShapes(recursive: true)
//generate a ball
let ballModel = ModelEntity(mesh: .generateSphere(radius: 0.4))
as (Entity & HasCollision & HasPhysicsBody)
ballModel.generateCollisionShapes(recursive: true)
ballModel.position = [0,0, -1.5]
ballModel.physicsBody = .init()
ballModel.physicsBody?.mode = .dynamic
let sub = arView.scene.subscribe(to: CollisionEvents.Began.self,
on: ballModel) { _ in print("OCCURED!") }
subscriptions.append(sub)
anchor.addChild(ballModel)
anchor.addChild(planeModel)
arView.scene.addAnchor(anchor)
return arView
}
}

Answer 1

Collider and collidee
This code activates physics and prints "occured" N times, thanks to CollisionEvents' subscription:
import SwiftUI
import RealityKit
import Combine
struct ARViewContainer: UIViewRepresentable {
#State var subscriptions: [AnyCancellable] = []
let arView = ARView(frame: .zero)
let anchor = AnchorEntity()
func makeUIView(context: Context) -> ARView {
// PLANE
let planeModel = ModelEntity(mesh: .generatePlane(width: 2.0,
depth: 2.0))
as (Entity & HasPhysics)
planeModel.position = [0,-1,-1.5]
planeModel.generateCollisionShapes(recursive: false)
planeModel.physicsBody = .init()
planeModel.physicsBody?.mode = .static
// BALL
let ballModel = ModelEntity(mesh: .generateSphere(radius: 0.2),
materials: [UnlitMaterial()])
as (Entity & HasPhysics)
ballModel.position = [0, 1,-1.5]
ballModel.generateCollisionShapes(recursive: false)
ballModel.physicsBody = .init()
ballModel.physicsBody?.mode = .dynamic
DispatchQueue.main.async {
arView.scene.subscribe(to: CollisionEvents.Began.self,
on: ballModel) { _ in
print("OCCURED!")
}.store(in: &subscriptions)
}
anchor.addChild(ballModel)
anchor.addChild(planeModel)
arView.scene.addAnchor(anchor)
return arView
}
func updateUIView(_ view: ARView, context: Context) { }
}
struct ContentView : View {
var body: some View {
ARViewContainer().ignoresSafeArea()
}
}