Detect a vertical plane and project a video on it. An image is loaded as a placeholder and replaced by the video when 'play' button is pressed

ViewController.swift

// this code requires two assets, an image "ocean" and an mp4 "team-walking"

import UIKit
import ARKit
import SceneKit


class ViewController: UIViewController, ARSCNViewDelegate {

    // connections to storyboard
    @IBOutlet weak var sceneView: ARSCNView!
    @IBOutlet weak var buttonStart: UIButton!
    @IBOutlet weak var buttonStop: UIButton!
    
    // video player
    var player : AVPlayer?
    
    // standard world tracking config
    let configuration = ARWorldTrackingConfiguration()
    
    // used for video node
    let videoNode = SCNNode(geometry: SCNPlane())

    override func viewDidLoad() {
        super.viewDidLoad()
        
        // set delegate so renderer fn gets called
        sceneView.delegate = self
        // type of plane detection
        configuration.planeDetection = .vertical
        // run, requests camera access first run
        sceneView.session.run(configuration)
    }
    
    override func viewWillAppear(_ animated: Bool) {
        super.viewWillAppear(animated)
        // debug
        print("View will appear")
    }
        
    func createNode(planeAnchor: ARPlaneAnchor) -> SCNNode {
        
        // set width & height
        videoNode.geometry?.setValue(CGFloat(planeAnchor.extent.x), forKey: "width")
        videoNode.geometry?.setValue(CGFloat(planeAnchor.extent.z), forKey: "height")
        
        // now set node properties. The UIImage is a content placeholder, replaced by buttonStartTouch
        videoNode.geometry?.firstMaterial?.diffuse.contents = UIImage(named: "ocean")
        
        videoNode.geometry?.firstMaterial?.isDoubleSided = true
        videoNode.position = SCNVector3(planeAnchor.center.x, planeAnchor.center.y, planeAnchor.center.z)
        
        // rotate 90 degrees about x axis <--x-->
        videoNode.eulerAngles = SCNVector3(-90.degreesToRadians, 0, 0)
        return videoNode
    }
    
    
    @IBAction func buttonStartTouch(_ sender: Any) {
        // prepare the video reference
        let fileURL = URL(fileURLWithPath: Bundle.main.path(forResource: "team-walking", ofType: "mp4")!)
        player = AVPlayer(url: fileURL)
        videoNode.geometry?.firstMaterial?.diffuse.contents = player
        player!.play()
    }
    
    @IBAction func buttonStopTouch(_ sender: Any) {
        // haven't found 'stop' so using 'pause'
        player!.pause()
    }
    
    // This delegate fires when an anchor is added whenever an ARAnchor was added to the sceneview. An anchor encodes position, size and orientation of something ... the surface in this case.
    func renderer(_ renderer: SCNSceneRenderer, didAdd node: SCNNode, for anchor: ARAnchor) {
        print("New surface detected")
        
        // notice that we {return} early if we don't have an anchor
        guard let planeAnchor = anchor as? ARPlaneAnchor else {return}
        
        if (player?.timeControlStatus == AVPlayer.TimeControlStatus.playing) {
            print("playing, so not creating a new node")
            
        } else {
            // ... we proceed creating and adding the scene node
            let childNode = createNode(planeAnchor: planeAnchor)
            node.addChildNode(childNode)
        }
    }
    
    func renderer(_ renderer: SCNSceneRenderer, didUpdate node: SCNNode, for anchor: ARAnchor) {
        print("Surface updated")

        guard let planeAnchor = anchor as? ARPlaneAnchor else {return}

        if (player?.timeControlStatus == AVPlayer.TimeControlStatus.playing) {
            
            print("playing, so not updating nodes")
            
        } else {
            // remove all
            node.enumerateChildNodes { (childNode, _) in
                childNode.removeFromParentNode()
            }
            // add back
            let childNode = createNode(planeAnchor: planeAnchor)
            node.addChildNode(childNode)
        }
    }
    
    func renderer(_ renderer: SCNSceneRenderer, didRemove node: SCNNode, for anchor: ARAnchor) {
        print("Surface anchor removed")
        // remove all
        
        if (player?.timeControlStatus == AVPlayer.TimeControlStatus.playing) {
            print("playing, so not removing nodes")
        } else {
        
            node.enumerateChildNodes { (childNode, _) in
                childNode.removeFromParentNode()
            }
        }
    }

}

extension Int {
    var degreesToRadians: Double { return Double(self) * .pi/180 }
}