CLLocationManager致命错误：在展开可选值Swift时意外发现nil

Question

我有一个问题，因为我的应用程序崩溃，当我试图获得位置用户并在我的.plist中获得我的代码的权限。

import UIKit
import MapKit
import CoreLocation

class mapClass : UIViewController,MKMapViewDelegate,CLLocationManagerDelegate{

    var location4 = CLLocation()
    var lm  = CLLocationManager ()

    @IBOutlet  var propMapa: MKMapView!

    lm.delegate=self
    lm.desiredAccuracy = kCLLocationAccuracyNearestTenMeters
    lm.distanceFilter = kCLDistanceFilterNone
    lm.startUpdatingLocation()

    println("\(lm.location)") <---- nil

   location4 = lm.location <---- crash

}

日志：致命错误：在展开Optional值时意外发现nil

Answer 1

在调用lm.startUpdatingLocation() ，位置管理器会在检测到位置更改时调用didUpdateLocations() ，因此您需要实现CLLocationManager::didUpdateLocations来检索位置：

import UIKit
import MapKit
import CoreLocation

class mapClass : UIViewController,MKMapViewDelegate,CLLocationManagerDelegate{

    var location4 = CLLocation()
    var lm  = CLLocationManager ()

    @IBOutlet  var propMapa: MKMapView!

    ...

    lm.delegate=self
    lm.desiredAccuracy = kCLLocationAccuracyNearestTenMeters
    lm.distanceFilter = kCLDistanceFilterNone
    lm.startUpdatingLocation()
}

func locationManager(manager: CLLocationManager!, didUpdateLocations locations: [AnyObject]!) {

    let currentLocation = locations.last as CLLocation
    println(currentLocation)
    ...
}

Answer 2

import UIKit
import MapKit
import CoreLocation
class ViewController: UIViewController,MKMapViewDelegate,CLLocationManagerDelegate
{
    @IBOutlet weak var mapView: MKMapView!
    @IBOutlet weak var textField: UITextField!
    @IBOutlet weak var searchButton: UIButton!
    let locationManager = CLLocationManager()
    var location:CLLocationCoordinate2D!

    override func viewDidLoad() {
        super.viewDidLoad()

        println("Search Button Clicked");
        mapView.showsUserLocation = true;
    }

    override func didReceiveMemoryWarning() {
        super.didReceiveMemoryWarning()
        // Dispose of any resources that can be recreated.
    }

    @IBAction func searchButtonClicked(sender:AnyObject)
    {
        locationManager.distanceFilter = kCLDistanceFilterNone
        locationManager.desiredAccuracy = kCLLocationAccuracyBest
        locationManager.delegate = self

        locationManager.requestWhenInUseAuthorization()

        locationManager.startUpdatingLocation()
    }

    func locationManager(manager: CLLocationManager!, didUpdateLocations locations: [AnyObject]!) {

        println("delegate called")
        if manager.location != nil
        {
            println(locationManager.location.coordinate.latitude)
            let artwork = Artwork(title: "Ram",
                locationName: "Infotech",
                discipline: "Testing",
                coordinate: CLLocationCoordinate2D(latitude:manager.location.coordinate.latitude, longitude:manager.location.coordinate.longitude))

            mapView.addAnnotation(artwork)
        }

    }

    func locationManager(manager: CLLocationManager!, didFailWithError error: NSError!)
    {

        println(error)
    }
}

Answer 3

Acces控制可能尚未完成。 您可以检查autorisation是否可用。

func locationManager(_ manager: CLLocationManager, didChangeAuthorization status: CLAuthorizationStatus) {
    if CLLocationManager.locationServicesEnabled() {
        switch CLLocationManager.authorizationStatus() {
        case .notDetermined, .restricted, .denied:
            print("No access")
        case .authorizedAlways, .authorizedWhenInUse:
            let sourceCoordinate = locationManager.location?.coordinate
            showRouteOnMap(pickupCoordinate: sourceCoordinate!, destinationCoordinate: CLLocationCoordinate2DMake(41.037141,28.9834662))
        }
    } else {
        print("Location services are not enabled")
    }
}