斯威夫特4添加注释错误意外发现零，同时展开

Question

我只是想注释添加到我的地图的看法，但我一直运行到这个错误“意外发现零，同时展开”，我似乎无法来解决这个问题或发现在我的情况下，有效的解决方案。可能有人请告诉我在哪里出了问题。提前致谢。我已经尝试改变var mapView: MKMapView!没有成功var mapView: MKMapView?

class customPin: NSObject, MKAnnotation {
var coordinate: CLLocationCoordinate2D
var title: String?
var subtitle: String?

init(pinTitle:String, pinSubTitle:String, location:CLLocationCoordinate2D) {
    self.title = pinTitle
    self.subtitle = pinSubTitle
    self.coordinate = location
}
}

var mapView: MKMapView!
var locationManager = CLLocationManager()

override func viewDidLoad() {
    super.viewDidLoad()

    let location = CLLocationCoordinate2D(latitude: 32.2325, longitude:76.3242)
    let region = MKCoordinateRegion(center: location, span: MKCoordinateSpan(latitudeDelta: 0.005, longitudeDelta: 0.005))
    self.mapView.setRegion(region, animated: true)

    let pin = customPin(pinTitle: "Honory Dalailama Temple", pinSubTitle: "Dharamshala, Himachal Pradesh, India", location: location)
    self.mapView.addAnnotation(pin)
    self.mapView.delegate = self
}


func mapView(_ mapView: MKMapView, viewFor annotation: MKAnnotation) -> MKAnnotationView? {
    if annotation is MKUserLocation {
        return nil
    }

    let annotationView = MKAnnotationView(annotation: annotation, reuseIdentifier: "customannotation")
    annotationView.image = UIImage(named:"pin")
    annotationView.canShowCallout = true
    return annotationView
}

func mapView(_ mapView: MKMapView, didSelect view: MKAnnotationView) {
    print("annotation title == \(String(describing: view.annotation?.title!))")
}

fileprivate func setupLocationManager() {self.locationManager.requestWhenInUseAuthorization()

    if CLLocationManager.locationServicesEnabled() == true {

        if CLLocationManager.authorizationStatus() == .restricted || CLLocationManager.authorizationStatus() == .denied || CLLocationManager.authorizationStatus() == .notDetermined {

            locationManager.requestWhenInUseAuthorization()
        }

        locationManager.desiredAccuracy = 1.0
        locationManager.delegate = self
        locationManager.startUpdatingLocation()

    } else {
        print("PLease turn on location services or GPS")
    }

}

fileprivate func setupMapView() {
    let mView = MKMapView(frame: CGRect(x: 0, y: 20, width: view.frame.width, height: view.frame.height))
    mView.showsUserLocation = true
    view.addSubview(mView)
    mView.showsScale = true
    mView.showsPointsOfInterest = true
    mView.showsTraffic = true
    mView.showsCompass = true
    mView.userTrackingMode = .follow
    self.mapView = mView
}

}

Answer 1

这看起来车：

print("annotation title == \(String(describing: view.annotation?.title!))")

如果annotation是零，你力!展开它，这将导致该崩溃。

改用：

print("annotation title == \(String(describing: view.annotation?.title))")

---

这也不清楚，你已经叫setupMapView()和实际设置mapView被调用之前viewDidLoad()。在viewDidLoad()添加一行：

if mapView == nil { setupMapView() }

使用前mapView。