在swift中将注释从一个视图传递到另一个视图

我想将注释从ViewController传递到ARViewController，并将其显示在地图上。当我按下segue按钮时，我收到一条Nil错误消息：（以下是我在ViewController中的内容

var startPt = POIs(coordinate: CLLocationCoordinate2D(latitude: Double("")!, longitude: Double("")! ))

func mapView(_ mapView: MKMapView, annotationView view: MKAnnotationView,
    calloutAccessoryControlTapped control: UIControl) {

    let storyboard = UIStoryboard(name: "Main", bundle:nil)
    let viewController = storyboard.instantiateViewController(withIdentifier : "ARV")
    self.present(viewController, animated: true)
  //location.mapItem().openInMaps(launchOptions: launchOptions)
}

override func prepare(for segue: UIStoryboardSegue, sender: Any?) {
    //guard let ViewController = segue.destination as? ARViewController,
    if segue.identifier == "ARV"{

        let vc = segue.destination as! ARViewController
        vc.dest = startPt
    }
}

var dest = POIs(coordinate: CLLocationCoordinate2D(latitude: Double("")!, longitude: Double("")! ))


override func viewDidLoad() {
    super.viewDidLoad()


    //show the user's current location
    mapView.userTrackingMode = .follow

    mapView.delegate = self as? MKMapViewDelegate

    mapView.addAnnotation(dest)
}

这就是我在ARViewController中看到的

var startPt = POIs(coordinate: CLLocationCoordinate2D(latitude: Double("")!, longitude: Double("")! ))

func mapView(_ mapView: MKMapView, annotationView view: MKAnnotationView,
    calloutAccessoryControlTapped control: UIControl) {

    let storyboard = UIStoryboard(name: "Main", bundle:nil)
    let viewController = storyboard.instantiateViewController(withIdentifier : "ARV")
    self.present(viewController, animated: true)
  //location.mapItem().openInMaps(launchOptions: launchOptions)
}

override func prepare(for segue: UIStoryboardSegue, sender: Any?) {
    //guard let ViewController = segue.destination as? ARViewController,
    if segue.identifier == "ARV"{

        let vc = segue.destination as! ARViewController
        vc.dest = startPt
    }
}

var dest = POIs(coordinate: CLLocationCoordinate2D(latitude: Double("")!, longitude: Double("")! ))


override func viewDidLoad() {
    super.viewDidLoad()


    //show the user's current location
    mapView.userTrackingMode = .follow

    mapView.delegate = self as? MKMapViewDelegate

    mapView.addAnnotation(dest)
}

---

您正在手动显示目标视图控制器，而不是执行序列，因此不会调用

prepare（for:sender:）

您有两个选择：

在演示之前，只需在

calloutAccessoryControlTapped

中设置

dest

属性，例如：

let viewController = storyboard.instantiateViewController(withIdentifier : "ARV") as! ARViewController
viewController.dest = ...

或

不要实例化视图控制器，而是以编程方式执行您在这两个视图控制器之间定义的序列（在本例中，我假设您已经为序列本身提供了自己的故事板标识符

ARV

），例如

如果您这样做，

prepare（for:sender:）

将被调用。FWIW，我看不到您在哪里设置

startPt