AVImageDetection.swift

func renderer(_ renderer: SCNSceneRenderer, nodeFor anchor: ARAnchor) -> SCNNode? {
        let node = SCNNode()
        if let imageAnchor = anchor as? ARImageAnchor {
            let plane = SCNPlane(width: imageAnchor.referenceImage.physicalSize.width, height: imageAnchor.referenceImage.physicalSize.height)
            plane.firstMaterial?.diffuse.contents = UIColor(white: 1, alpha: 0.8)
            let material = SCNMaterial()
            material.diffuse.contents = viewObj
            plane.materials = [material]
            let planeNode = SCNNode(geometry: plane)
            planeNode.eulerAngles.x = -.pi / 2
            node.addChildNode(planeNode)
        } else {
            if isFirstTime == true{
                isFirstTime = false
            } else {
                return node
            }
            let plane = SCNPlane(width: 5, height: 5)
            plane.firstMaterial?.diffuse.contents = UIColor(white: 1, alpha: 1)
            let planeNode = SCNNode(geometry: plane)
            planeNode.eulerAngles.x = .pi
            let shipScene = SCNScene(named: "art.scnassets/Sphere.scn")!
            let shipNode = shipScene.rootNode.childNodes.first!
            shipNode.position = SCNVector3Zero
            shipNode.position.z = 0.15
            planeNode.addChildNode(shipNode)
            node.addChildNode(planeNode)
        }
        return node
    }