在地图上添加面向恒定方向的MKPointAnnotation

Question

我正在尝试添加带有始终指向自定义方向的自定义图片的MKAnnotation。 MKAnnotationView的image属性没有提供关于此主题的清晰信息。

我有两个主要要求：

1）相机必须遵循用户的标题

2）箭头必须始终相对于真北指向30°

这是我的最低测试代码：

class ViewController: UIViewController, MKMapViewDelegate, CLLocationManagerDelegate {

let targetDirection: CLLocationDirection = 30.0

var headingAnnotationView: MKAnnotationView?
var currentHeading: CLLocationDegrees = 0.0

var mapView: MKMapView!
private let id = "FixedRotation"
let targetCoordinates = CLLocationCoordinate2D(latitude: 48.847229, longitude: 2.361474)

override func viewDidLoad() {
    super.viewDidLoad()

    self.mapView = MKMapView(frame: UIScreen.main.bounds)
    self.mapView.delegate = self
    self.view.addSubview(self.mapView)

    let annotation = MKPointAnnotation.init()
    annotation.title = id
    annotation.coordinate = self.targetCoordinates
    self.mapView.addAnnotation(annotation)
    self.mapView.setRegion(MKCoordinateRegion(center: self.targetCoordinates, latitudinalMeters: 1000, longitudinalMeters: 1000), animated: false)

    let locationManager = CLLocationManager()
    locationManager.delegate = self
    locationManager.requestWhenInUseAuthorization()
    locationManager.startUpdatingHeading()
}

func mapView(_ mapView: MKMapView, didAdd views: [MKAnnotationView]) {
    guard let annotationView = views.last else { return }
    if annotationView.reuseIdentifier == id {
        self.headingAnnotationView = annotationView
    }
}

func mapView(_ mapView: MKMapView, viewFor annotation: MKAnnotation) -> MKAnnotationView? {
    let annotationView: MKAnnotationView = mapView.dequeueReusableAnnotationView(withIdentifier: id) ?? MKAnnotationView.init(annotation: annotation, reuseIdentifier: id)
    let image = UIImage(named: "guidance-arrow")!
    annotationView.image = image
    return annotationView
}

func locationManager(_ manager: CLLocationManager, didUpdateHeading newHeading: CLHeading) {
    self.currentHeading = newHeading.trueHeading
    let rotationRad = atan2(self.mapView.transform.b, self.mapView.transform.a)

    DispatchQueue.main.async {
        self.mapView.camera.heading = CLLocationDirection(rotationRad)
        self.headingAnnotationView?.transform = CGAffineTransform(rotationAngle: CGFloat(targetDirection.degreesToRadians) - rotationRad)
    }
}

}

我不知道如何解决它。