It works on Metal.

In macOS use Tab View (for example) for accommodation of SceneView and NSImageView.

I used Xcode 11.4 on macOS 10.15.4 Catalina.

import SceneKitimport Cocoaclass ViewController: NSViewController {        @IBOutlet var sceneView: SCNView!    @IBOutlet var imageView: NSImageView!        override func viewDidLoad() {        super.viewDidLoad()                sceneView.scene = SCNScene()                sceneView.pointOfView?.position.z = 20        sceneView.allowsCameraControl = true        sceneView.showsStatistics = true        sceneView.backgroundColor = NSColor.black        sceneView.autoenablesDefaultLighting = true        let box = SCNBox(width: 1.0,                        height: 1.0,                        length: 1.0,                 chamferRadius: 0.0)                box.firstMaterial?.diffuse.contents = NSColor.systemTeal        let boxNode = SCNNode(geometry: box)        boxNode.position = SCNVector3(0,0,-10)        sceneView.scene!.rootNode.addChildNode(boxNode)    }        @IBAction func createSnapshot(_ sender: NSButton) {        let image = sceneView.snapshot()        imageView.image = image    }}