Swift - User Location Issues - ios

Question

I've just started with swift and I'm having an issue. I've read the various threads about user location and map kits and can't solve my issue. I had the code running and could create regions as I wanted and I could zoom into the user location.
I've paired the code back to try and locate the issue and the code left is below. The issue is that the userlocation is coming back as a nil value when you try and run the simulator which crashes the app. What am I doing wrong as I've completed authorising user location so surely it shouldn't be coming back nil. At one point I had code to zoom on the user location AFTER initially setting a region elsewhere and calling a function to do the zoom, but if you initially try and call the user location its always nil so you can't initialise the map zooming into where the user is which is what I want.
import UIKit
import MapKit
class MapController: UIViewController, CLLocationManagerDelegate {
#IBOutlet weak var mapView: MKMapView!
// MARK: - location manager to authorize user location for Maps app
var locationManager = CLLocationManager()
func checkLocationAuthorizationStatus() {
if CLLocationManager.authorizationStatus() == .AuthorizedWhenInUse {
mapView.showsUserLocation = true
} else {
locationManager.requestWhenInUseAuthorization()
}
}
override func viewDidLoad() {
super.viewDidLoad()
checkLocationAuthorizationStatus()
var userLocation = locationManager.location
println("\(userLocation.coordinate.latitude)")
println("\(userLocation.coordinate.longitude)")
// Do any additional setup after loading the view.
}
}

Answer 1

Firstly, CLLocationManager updates user location asynchronously. That means that even after you call startUpdatingLocation() your location will be nil until location manager returns with the new location.
Secondly, in your code you are not actually calling this method. If you DO need to be able to store the user location then you should change your code to:
import UIKit
import MapKit
class MapController: UIViewController, CLLocationManagerDelegate {
#IBOutlet weak var mapView: MKMapView!
// MARK: - location manager to authorize user location for Maps app
lazy var locationManager: CLLocationManager = {
var manager = CLLocationManager()
manager.delegate = self
return manager
}()
func checkLocationAuthorizationStatus() {
if CLLocationManager.authorizationStatus() == .AuthorizedWhenInUse {
mapView.showsUserLocation = true
locationManager.startUpdatingLocation()
} else {
locationManager.requestWhenInUseAuthorization()
}
}
override func viewDidLoad() {
super.viewDidLoad()
checkLocationAuthorizationStatus()
//location is nil at this point because location update is
//an asynchronous operation!
//var userLocation = locationManager.location
//println("\(userLocation.coordinate.latitude)")
//println("\(userLocation.coordinate.longitude)")
// Do any additional setup after loading the view.
}
func locationManager(manager: CLLocationManager, didUpdateLocations locations: [CLLocation]) {
if let location = locations.last {
//this is the place where you get the new location
println("\(location.coordinate.latitude)")
println("\(location.coordinate.longitude)")
}
}
There is only one minor thing to note. In the last function I am using an argument locations: [CLLocation]. This is definitely correct in Swift 2.0, but in Swift 1.2 it might be locations: [AnyObject] in which case you have to do a conditional downcast yourself.
Let me know if this works for you