ARKit和RealityKit是苹果公司的两个增强现实（AR）框架。ARKit是一个用于创建基于现实的AR应用的框架，而RealityKit是一个用于创建虚拟现实（VR）和AR应用的框架。

ARKit提供了强大的AR功能，如空间感知、多平面检测和灯光估算等。这些功能使得开发者能够创建高品质的AR应用，使用现实感十足的3D模型来丰富用户体验。

下面是一个简单的ARKit代码示例：

import UIKit
import ARKit

class ViewController: UIViewController, ARSCNViewDelegate {

    @IBOutlet var sceneView: ARSCNView!

    override func viewDidLoad() {
        super.viewDidLoad()

        // Set the view's delegate
        sceneView.delegate = self

        // Show statistics such as fps and timing information
        sceneView.showsStatistics = true

        // Create a new scene
        let scene = SCNScene(named: "art.scnassets/ship.scn")!

        // Set the scene to the view
        sceneView.scene = scene
    }

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

        // Create a session configuration
        let configuration = ARWorldTrackingConfiguration()

        // Run the view's session
        sceneView.session.run(configuration)
    }

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

        // Pause the view's session
        sceneView.session.pause()
    }

    // MARK: - ARSCNViewDelegate

    // Override to create and configure nodes for anchors added to the view's session.
    func renderer(_ renderer: SCNSceneRenderer, nodeFor anchor: ARAnchor) -> SCNNode? {
        let node = SCNNode()

        return node
    }

    func session(_ session: ARSession, didFailWithError error: Error) {
        // Present an error message to the user
    }

    func sessionWasInterrupted(_ session: ARSession) {
        // Inform the user that the session has been interrupted, for example, by presenting an overlay
    }

    func sessionInterruptionEnded(_ session: ARSession) {
        // Reset tracking and/or remove existing anchors if consistent tracking is required
    }
}

RealityKit则提供了一套强大的工具，用于构建高级AR/VR游戏和应用，包括物理模拟、光线跟