ios - CLLocationManager fatal error : unexpectedly found nil while unwrapping an Optional value Swift

Question

我有一个问题，因为当我尝试获取位置用户并在我的 .plist 中获得权限时，我的应用程序崩溃了，这是我的代码。

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: fatal error :在展开可选值时意外发现 nil

Answer 1

调用 lm.startUpdatingLocation() 后，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 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)
    ...
}