requestLocation没有调用didUpdateLocations

Question

First of all: I know there are similar threads here on So, but nothing thats suggested works for me.

Here is what i am trying to do: I want to have a PositionController(Class) that controls the users current position and gives interfaces for other classes,ViewControllers etc to use the information.

Currently i have this code implemented:

import Foundation
import CoreLocation

class PositionController: CLLocationManager, CLLocationManagerDelegate{

    let locationManager: CLLocationManager

    override init() {
        self.locationManager = CLLocationManager()
        print("---------------Init---------------------------")
    }

    func getPosition(){

        locationManager.delegate = self
        locationManager.requestWhenInUseAuthorization()
        locationManager.desiredAccuracy = kCLLocationAccuracyKilometer
        locationManager.requestLocation()
    }

    func locationManager(_ manager: CLLocationManager, didFailWithError error: Error) {
        print(error)
     }

    func locationManager(_ mnager: CLLocationManager, didUpdateLocations locations: [CLLocation]) {
        print(locations)
    }
}

Note that the print statements in the delegate functions are only placeholders at the moment. Also note that i want the getPosition-Method to be called from outside ViewControllers. But when i call the function it just goes through the codeblock without calling neither of the two delegate functions at the end.

Further i have "Privacy - Location When In Use Description" and "Location Usage Description" added to my plist. I really dont know what i am missing or doing wrong, so all help is appreciated

EDIT:

import UIKit
import GoogleMaps
import GoogleMaps


class MapViewController: UIViewController, CLLocationManagerDelegate {

override func viewDidLoad() {
    super.viewDidLoad()
    // Do any additional setup after loading the view, typically from a nib.

    // For use in foreground

    print("-----------------------In------------------------")
    let positionController = PositionController()
    positionController.getPosition()
    print("-----------------------Out------------------------")

    let camera = GMSCameraPosition.camera(withLatitude: 48.137154
                                          longitude: 11.576124, zoom:12)
    let mapView = GMSMapView.map(withFrame: CGRect.zero, camera:camera)
    let marker = GMSMarker()

    marker.position = camera.target
    marker.snippet = "Munich"
    marker.appearAnimation = GMSMarkerAnimation.pop
    marker.map = mapView

    self.view = mapView

}

Answer 1

Your problem is that you are creating an instance of PositionController as a local variable in viewDidLoad . viewDidLoad will exit, deallocating the PositionController instance before the location callback gets a chance to execute (Determine location can take quite a few seconds or even longer).

If you use a property to hold your PositionController reference then it will have the same lifetime as your view controller object:

class MapViewController: UIViewController, CLLocationManagerDelegate {

    let positionController = PositionController()  

    override func viewDidLoad() {
        super.viewDidLoad()
        // Do any additional setup after loading the view, typically from a nib.

        // For use in foreground

        print("-----------------------In------------------------")
        self.positionController.getPosition()
        print("-----------------------Out------------------------")

        let camera = GMSCameraPosition.camera(withLatitude: 48.137154
                                              longitude: 11.576124, zoom:12)
        let mapView = GMSMapView.map(withFrame: CGRect.zero, camera:camera)
        let marker = GMSMarker()

        marker.position = camera.target
        marker.snippet = "Munich"
        marker.appearAnimation = GMSMarkerAnimation.pop
        marker.map = mapView

        self.view = mapView

    }

You probably want to have a single instance of PositionController in your app. You could make it a property of your AppDelegate or make it a singleton in its own right (Singletons can create issues with mockability and testing, so I will leave it up to you to decide how you want to do it).