AR实景地图代码

AR实景地图需要使用AR技术和地图API技术进行开发，下面是一个简单的AR实景地图的代码实现：

import UIKit
import ARKit
import MapKit

class ViewController: UIViewController, ARSCNViewDelegate {

    @IBOutlet weak var sceneView: ARSCNView!
    var locationManager = CLLocationManager()
    var userLocation: CLLocation?
    var annotations = [CLLocationCoordinate2D]()

    override func viewDidLoad() {
        super.viewDidLoad()

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

        // Create a new scene
        let scene = SCNScene()

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

        // Request location authorization
        locationManager.requestWhenInUseAuthorization()

        // Set up location manager
        locationManager.delegate = self
        locationManager.desiredAccuracy = kCLLocationAccuracyBest
        locationManager.startUpdatingLocation()

        // Set up map annotations
        let annotation1 = CLLocationCoordinate2D(latitude: 37.7749, longitude: -122.4194)
        let annotation2 = CLLocationCoordinate2D(latitude: 40.7128, longitude: -74.0060)
        let annotation3 = CLLocationCoordinate2D(latitude: 51.5074, longitude: 0.1278)
        annotations.append(annotation1)
        annotations.append(annotation2)
        annotations.append(annotation3)
    }

    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()
    }

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

        // Create a plane node
        let planeNode = SCNNode()
        planeNode.geometry = SCNPlane(width: CGFloat(planeAnchor.extent.x), height: CGFloat(planeAnchor.extent.z))
        planeNode.eulerAngles.x = -.pi / 2
        planeNode.opacity = 0.25

        // Add plane node to scene
        node.addChildNode(planeNode)

        // Add map annotations
        for annotation in annotations {
            let annotationNode = SCNNode()
            annotationNode.geometry = SCNBox(width: 0.1, height: 0.1, length: 0.1, chamferRadius: 0)
            annotationNode.geometry?.firstMaterial?.diffuse.contents = UIColor.red
            annotationNode.position = getRelativePosition(absoluteCoordinate: annotation, userLocation: userLocation!)
            node.addChildNode(annotationNode)
        }
    }

    func getRelativePosition(absoluteCoordinate: CLLocationCoordinate2D, userLocation: CLLocation) -> SCNVector3 {
        let lat1 = userLocation.coordinate.latitude
        let lon1 = userLocation.coordinate.longitude
        let lat2 = absoluteCoordinate.latitude
        let lon2 = absoluteCoordinate.longitude

        let x = (lon2 - lon1) * cos((lat1 + lat2) / 2)
        let y = lat2 - lat1
        let z = userLocation.distance(from: CLLocation(latitude: lat2, longitude: lon2))

        return SCNVector3(x, y, -Float(z))
    }
}

extension ViewController: CLLocationManagerDelegate {
    func locationManager(_ manager: CLLocationManager, didUpdateLocations locations: [CLLocation]) {
        guard let location = locations.last else { return }
        userLocation = location
    }
}

这个代码实现了在AR场景中显示地图的功能，并且根据用户当前位置和给定的地图标记点，计算出它们在AR场景中的相对位置。但是需要注意的是，这只是一个简单的示例，实际的AR实景地图还需要考虑很多因素，如地图数据的更新、AR场景的稳定性等。