Swift RealityKit – 无法加载 ARView(发现为零)

我有见识和经验.我试图在VC中打开的rcproject文件，但问题是我的屏幕变黑了.为什么？

import RealityKit
import UIKit
import ARKit

class ArVC: UIViewController, ARSCNViewDelegate {
    
    lazy var sceneView: ARSCNView = {
        let sceneView = ARSCNView()
        sceneView.delegate = self
        return sceneView
    }()
    
    var arView: ARView = {
        let arView = ARView()
        let boxAnchor = try! Experience.loadBox()
        arView.scene.anchors.append(boxAnchor)
        return arView
    }()

    override func viewDidLoad() {
        super.viewDidLoad()
        self.view.backgroundColor = .clear
    }
    
    func createView() {
        self.view.addSubview(sceneView)
        self.view.addSubview(self.sceneView)
        self.sceneView.snp.makeConstraints { make in
            make.centerY.centerX.equalToSuperview()
        }
        
        view.subviews.forEach {
            $0.translatesAutoresizingMaskIntoConstraints = false
        }
        
        self.sceneView.addSubview(self.arView)
        self.arView.snp.makeConstraints { make in
            make.centerX.centerY.equalToSuperview()
        }
    }
}

还有哪些其他选项可以通过编程方式设置ARView？非常感谢.