SWIFT4.1中的locationManager展开错误但SWIFT4.0中没有

Question

我有自己在SWIFT4.0中编写的代码，它允许我正在开发的应用程序显示一个具有目的地和用户位置的Map。现在，这个应用程序在斯威夫特4.1的最新更新之前运行得很好。

错误消息显示，在展开可选值时，意外地发现为零。在xCode输出窗口中，它显示了以下文本：

无法从角4 (lldb)嵌入法律属性

我已经尝试过各种各样的事情，并在互联网上查找这个，我不确定这是否是Swift 4.1中的一个bug，还是有一些我需要做的新的事情。就像前面说的，这个应用程序以前运行得很好。

我还确保info.plist具有应用于Location的正确的隐私属性。

Info.plist

import UIKit
import MapKit
import CoreLocation

class MapViewController: UIViewController, MKMapViewDelegate, CLLocationManagerDelegate {

@IBAction func centerUserLocation(_ sender: Any) {
    mapkitView.setUserTrackingMode(MKUserTrackingMode.follow, animated: true)
}

    @IBOutlet weak var mapkitView: MKMapView!

let locationManager = CLLocationManager()

@IBAction func phoneNumber(_ sender: Any) {
    let number = "00436641491000"
    if let url = URL(string: "tel://\(number)") {
        UIApplication.shared.open(url)
    }
}

@IBAction func emailAddress(_ sender: Any) {
    let email = "salzburg@citybeats.at"
    if let url = URL(string: "mailto:\(email)") {
        UIApplication.shared.open(url)
    }
}

override func viewDidLoad() {
    super.viewDidLoad()

    mapkitView.delegate = self
    mapkitView.showsScale = true
    mapkitView.showsPointsOfInterest = true
    mapkitView.showsUserLocation = true
    mapkitView.userTrackingMode = .follow

    locationManager.requestAlwaysAuthorization()
    locationManager.requestWhenInUseAuthorization()

    if CLLocationManager.locationServicesEnabled(){
        locationManager.delegate = self
        locationManager.desiredAccuracy = kCLLocationAccuracyBest
        locationManager.startUpdatingLocation()
    }

    let sourceCoordinates = locationManager.location?.coordinate
    let destCoordinates = CLLocationCoordinate2DMake(47.800715, 13.041061)

    let sourcePlacemark = MKPlacemark(coordinate: sourceCoordinates!)
    let destPlacemark = MKPlacemark(coordinate: destCoordinates)

    let annotation = MKPointAnnotation()
    annotation.coordinate = destCoordinates
    annotation.title = "CityBeats"
    annotation.subtitle = "House & RnB"

    mapkitView.addAnnotation(annotation)



    let sourceItem = MKMapItem(placemark: sourcePlacemark)
    let destItem = MKMapItem(placemark: destPlacemark)

    let directionRequest = MKDirectionsRequest()
    directionRequest.source = sourceItem
    directionRequest.destination = destItem
    directionRequest.transportType = .walking

    let directions = MKDirections(request: directionRequest)
    directions.calculate(completionHandler: {
        response, error in

        guard let response = response else {
            if let error = error {
                print("Something went wrong!")
            }
            return
        }

        let route = response.routes[0]
        self.mapkitView.add(route.polyline, level: .aboveRoads)

        let rekt = route.polyline.boundingMapRect
        self.mapkitView.setRegion(MKCoordinateRegionForMapRect(rekt), animated: true)
    })
}

func mapView(_ mapView: MKMapView, rendererFor overlay: MKOverlay) -> MKOverlayRenderer {
    let renderer = MKPolylineRenderer(overlay: overlay)
    renderer.strokeColor = UIColor.cyan
    renderer.alpha = 0.7
    renderer.lineWidth = 7.0

    return renderer
    }
}

Answer 1

您应该检查sourceCoordinates是否为零。

例如：

guard let sourceCoordinates = locationManager.location?.coordinate else {
    return
}