在ARKit中，可以使用ARPlaneAnchor来检测和追踪平面。以下是一个示例代码，展示了如何使用ARKit检测平面：

import ARKit

class ViewController: UIViewController, ARSCNViewDelegate {

    @IBOutlet var sceneView: ARSCNView!

    override func viewDidLoad() {
        super.viewDidLoad()

        sceneView.delegate = self

        let configuration = ARWorldTrackingConfiguration()
        configuration.planeDetection = .horizontal
        sceneView.session.run(configuration)
    }

    override func viewWillAppear(_ animated: Bool) {
        super.viewWillAppear(animated)

        let configuration = ARWorldTrackingConfiguration()
        configuration.planeDetection = .horizontal
        sceneView.session.run(configuration)
    }

    override func viewWillDisappear(_ animated: Bool) {
        super.viewWillDisappear(animated)

        sceneView.session.pause()
    }

    func renderer(_ renderer: SCNSceneRenderer, didAdd node: SCNNode, for anchor: ARAnchor) {
        guard let planeAnchor = anchor as? ARPlaneAnchor else { return }

        let planeNode = createPlaneNode(center: planeAnchor.center, extent: planeAnchor.extent)
        node.addChildNode(planeNode)
    }

    func createPlaneNode(center: simd_float3, extent: simd_float3) -> SCNNode {
        let planeGeometry = SCNPlane(width: CGFloat(extent.x), height: CGFloat(extent.z))
        let planeNode = SCNNode(geometry: planeGeometry)
        planeNode.position = SCNVector3(center.x, 0, center.z)
        planeNode.eulerAngles.x = -.pi / 2
        planeNode.opacity = 0.5

        return planeNode
    }
}

这段代码中，首先在viewDidLoad和viewWillAppear方法中配置了ARWorldTrackingConfiguration，并开启了水平平面检测。然后在renderer(_:didAdd:for:)方法中，通过判断ARAnchor是否为ARPlaneAnchor来创建平面节点，并将其添加到场景中。

此外，还可以在ARSCNViewDelegate中的其他方法中处理平面更新，例如当检测到新的平面时，在renderer(_:didUpdate:for:)方法中更新平面节点的位置和大小。

希望这个示例代码能帮到你！