Unable to activate constraint with anchors

Question

So, I'm trying to create a sceneView programatically

class ViewController: UIViewController, ARSCNViewDelegate {
    var sceneView: ARSCNView = ARSCNView()
    let configuration = ARWorldTrackingConfiguration()

    override func viewDidLoad() {
        super.viewDidLoad()

        self.sceneView.debugOptions = [ARSCNDebugOptions.showFeaturePoints, ARSCNDebugOptions.showWorldOrigin]
        self.configuration.planeDetection = .horizontal
        self.sceneView.session.run(configuration)
        self.sceneView.delegate = self
        self.sceneView.autoenablesDefaultLighting = true

        //add autolayout contstraints
        self.sceneView.translatesAutoresizingMaskIntoConstraints = false
        self.sceneView.topAnchor.constraint(equalTo: self.view.topAnchor).isActive = true
        self.sceneView.leftAnchor.constraint(equalTo: self.view.leftAnchor).isActive = true
        self.sceneView.rightAnchor.constraint(equalTo: self.view.rightAnchor).isActive = true
        self.sceneView.bottomAnchor.constraint(equalTo: self.view.bottomAnchor).isActive = true

    }

    func renderer(_ renderer: SCNSceneRenderer, didAdd node: SCNNode, for anchor: ARAnchor) {
        guard anchor is ARPlaneAnchor else {return}
    }
}

But I get this error message:

Terminating app due to uncaught exception 'NSGenericException', reason: 'Unable to activate constraint with anchors and because they have no common ancestor. Does the constraint or its anchors reference items in different view hierarchies? That's illegal.'

It's happens in the part \\add autolayout contstraints. How can I add constraints to that element?

Answer 1

dan is right, you need to add sceneView as a subview before you can anchor it. Try something like this:

view.addSubview(sceneView)
sceneView.anchor(top: self.view.topAnchor, left: self.view.leftAnchor, bottom: self.view.bottomAnchor, right: self.view.rightAnchor, paddingTop: 0, paddingLeft: 0, paddingBottom: 0, paddingRight: 0, width: 0, height: 0)