Swift - 位置管理器无法立即使用

Question

So basically when the app loads it's supposed to center the map on the user location, but sometimes will get stuck at the guard let . Here is the code:

override func viewDidLoad() {
    super.viewDidLoad()
    mapView.delegate = self
    locationManager.delegate = self
    configureLocationServices()
    addDoubleTap()
}


//Center map around user location
func centerMapOnUserLocation(){
    print("In \(#function)")
    guard let coordinate = locationManager.location?.coordinate else { print("Error getting coordinate"); return}


    let coordinateRegion = MKCoordinateRegion.init(center: coordinate, latitudinalMeters: locationZoomRadius, longitudinalMeters: locationZoomRadius)
    mapView.setRegion(coordinateRegion, animated: true)

    //Setting local latitude and longitude variables to current location
    latitude = "\(coordinate.latitude)"
    longitude = "\(coordinate.longitude)"
    previewDataOnButton()
    print("Centered Map")
}

// MARK: - Location Services

//Request to enable location services
func configureLocationServices(){
    if authorizationStatus == .notDetermined{
        locationManager.requestAlwaysAuthorization()
    } else {
        return
    }
}

//If authorization changes then call centerMapOnUserLocation
func locationManager(_ manager: CLLocationManager, didChangeAuthorization status: CLAuthorizationStatus) {
    print("Authorization changed in \(#function). Calling centerMapOnUserLocation")
    centerMapOnUserLocation()
}

}

It seems to get stuck at the guard let in centerMapOnUserLocation() . This is shown through print statements:

Authorization changed in locationManager(_:didChangeAuthorization:). Calling centerMapOnUserLocation

In centerMapOnUserLocation()

Error getting coordinate

Im not sure how to fix this. Like I said sometimes it passes by the guard let and sometimes it gets stuck.

Answer 1

In you viewDidLoad add this line:

locationManager.startUpdatingLocation()

Then use this CLLocationManagerDelegate method:

func locationManager(_ manager: CLLocationManager, didUpdateLocations locations: [CLLocation]) {
    centerMapOnUserLocation()
}

You could pass in the locations into your method and move guard let before passing the location like this:

func locationManager(_ manager: CLLocationManager, didUpdateLocations locations: [CLLocation]) {
    guard let location = locations.last else { return }
    centerMapOnUserLocation(location: location.last)
}