Find a tapped childNode in 3D object in RealityKit

Hello,

You can hitTest your scene to determine the nearest entity that was hit (assuming this entity has an adequate collision shape), for example:

class GameViewController: NSViewController {
    
    @IBOutlet var arView: ARView!
    
    override func awakeFromNib() {
        
        let boxMesh = MeshResource.generateBox(size: 0.1)
        
        let anchor = AnchorEntity()
        anchor.name = "Anchor"
        
        // Creates a hierarchy of 10 boxes.
        var previousEntity: Entity = anchor
        for index in 1...10 {
            
            let model = ModelEntity(mesh: boxMesh)
            model.name = String("Box \(index)")
            
            model.transform.translation = .init(0.2, 0, 0)
            
            previousEntity.addChild(model)
            previousEntity = model
        }
        
        anchor.generateCollisionShapes(recursive: true)
        
        // Adds the hierarchy to the scene.
        arView.scene.addAnchor(anchor)

        arView.addGestureRecognizer(NSClickGestureRecognizer(target: self, action: #selector(clicked(_:))))        
    }
    
    @objc
    func clicked(_ sender: NSClickGestureRecognizer) {
        
        // Hit-tests the scene at the provided view location, returning only the closest hit collision shape. 
        let results = arView.hitTest(sender.location(in: arView), query: .nearest)
        
        guard let firstHitEntity = results.first?.entity else { return }
        
        // Logs the name of the hit entity.
        print(firstHitEntity.name)
    }
}

But I want to get the name of the tapped children ModelEntity, because my model is made of several other smaller objects. If i print the tapped object children, this is what I get. And I want to get the name of the tapped children not the main object.

That output indicates that your top-level 'arm' Entity has a collision shape that bounds all of its children.

Try setting arView.debugOptions = .showPhysics, and then post a screenshot of what your scene looks like with the collision shape visualization.