swift - 尝试在不提示位置授权的情况下启动 MapKit 位置更新

Question

在我的应用程序中，我使用 MKMapKit 和 MKUserTrackingBarButtonItem 来定位点击的用户。当我点击这个按钮时，输出控制台返回这个错误:

Trying to start MapKit location updates without prompting for location authorization. Must call -[CLLocationManager requestWhenInUseAuthorization] or -[CLLocationManager requestAlwaysAuthorization] first.

根据我的说法，此错误是由于 requestWhenInUseAuthorization() 尚未调用而引起的。事实上，MKUserTrackingBarButtonItem tap 调用函数 mapViewWillStartLocatingUser，它首先假定 CLLocationManager requestWhenInUseAuthorization:

 func mapViewWillStartLocatingUser(mapView: MKMapView!) {
    println("**** mapViewWillStartLocatingUser ****")

    // i servizi di localizzazione sono abilitati?
    if (CLLocationManager.locationServicesEnabled())
    {
        // setto il locationManager ed il delegate
        locationManager = CLLocationManager()
        locationManager.delegate = self

        // abbiamo l'autorizzazione ad accedere ai servizi di localizzazione?
        switch CLLocationManager.authorizationStatus(){
        case .Denied:
            // no
            displayAlertToEnableLocationServicesApp()
            //displayAlertWithTitle("Denied", message: "Location services are not allowed for this app")
        case .Restricted:
            // no
            displayAlertToEnableLocationServicesApp()
        case .NotDetermined:
            // bisogna chiedere all'utente
            println("Not Determined")
            if (locationManager != nil)
            {
                locationManager.requestWhenInUseAuthorization()
            }
        default:
            // si
            println("Authorized")
            if (locationManager != nil)
            {
                locationManager.desiredAccuracy = kCLLocationAccuracyBest
                locationManager.startUpdatingLocation()
            }
        }

    }
    else
    {
        println("Location services are not enabled")

        displayAlertWithTitle("Location Services are Turned Off", message: "Please open settings and turn on location services")
    }
}

// funzione della mappa
func mapView(mapView: MKMapView!, didFailToLocateUserWithError error: NSError!) {
    println("**** didFailToLocateUserWithError **** ", error)
}

// funzione della mappa
func mapView(mapView: MKMapView!, didChangeUserTrackingMode mode: MKUserTrackingMode, animated: Bool) {
    println("**** didChangeUserTrackingMode ****")
}

// funzione del CoreLocation che setta la visuale in base alla localizzaizone dell'utente
func locationManager(manager: CLLocationManager!, didUpdateLocations locations: [AnyObject]!) {
    println("**** didUpdateLocations ****")

    //self.mapView.showsUserLocation = true


    // aggiorno le coordinate dell'utente
    posizioneUtente = (locations[0] as CLLocation).coordinate
    //posizioneUtente = manager.location.coordinate
    println("Posizione utente aggiornata (lat: \(posizioneUtente.latitude) long: \(posizioneUtente.longitude))")

    // setto la camera sulla posizione dell'utente
    var camera = MKMapCamera(lookingAtCenterCoordinate: posizioneUtente, fromEyeCoordinate: posizioneUtente, eyeAltitude: 500)
    // utilizzo un'animazione più lenta
    UIView.animateWithDuration(1.8, animations:{
        self.mapView.camera = camera
    })

    locationManager.stopUpdatingLocation()

    // cambio l'icona del bottone della localizzazione
    //locationOutlet.setImage(UIImage(named: "LocalizzazioneEmpty"), forState: UIControlState.Normal)

}



// funzione del CoreLocation
func locationManager(manager: CLLocationManager!, didFailWithError error: NSError!)
{
    println("**** didFailWithError ****")
    println("Error: \(error.localizedDescription)")
}

// funzione del CoreLocation
func locationManager(manager: CLLocationManager!, didChangeAuthorizationStatus status: CLAuthorizationStatus) {
    print("The authorization status of location " + "services is changed to: ")

    switch CLLocationManager.authorizationStatus(){
    case .Denied:
        println("Denied")
    case .NotDetermined:
        println("Not determined")
    case .Restricted:
        println("Restricted")
    default:
        println("Authorized")
    }
}

我自然地添加了 Info.plist 键: NSLocationWhenInUseUsageDescription 。

我的问题是:如何在 MKUserTrackingBarButtonItem 点击但在 mapViewWillStartLocatingUser 启动之前调用 CLLocationManager requestWhenInUseAuthorization。我希望用户在点击按钮时得到提示，而 viewDidLoad

中没有

谢谢对不起我的英语

Answer 1

当您调用 requestWhenInUseAuthorization 时，系统会提示用户提供权限，但该权限尚未获得授权。一旦用户授予该权限，该问题将不会再次出现。

要对用户的响应使用react，您必须实现locationManager(_:didChangeAuthorizationStatus:) 来自 CLLocationManagerDelegate 协议(protocol)，只有在用户授予权限时才启动 startUpdateLocations()。