Simple example of setting up vertical and horizontal detected planes to occlude objects in SceneKit

ViewController+Occlusions.swift

import ARKit

extension ViewController {
	func renderer(_ renderer: SCNSceneRenderer, didAdd node: SCNNode, for anchor: ARAnchor) {
		guard let planeAnchor = anchor as? ARPlaneAnchor, let geom = ARSCNPlaneGeometry(device: MTLCreateSystemDefaultDevice()!) else {
			return
		}
		geom.update(from: planeAnchor.geometry)
		geom.firstMaterial?.colorBufferWriteMask = .alpha
		node.geometry = geom
	}

	func renderer(_ renderer: SCNSceneRenderer, didUpdate node: SCNNode, for anchor: ARAnchor) {
		if let planeAnchor = anchor as? ARPlaneAnchor, let geom = node.geometry as? ARSCNPlaneGeometry {
			geom.update(from: planeAnchor.geometry)
		}
	}
}