Can't get coordinates from CLLocationManager in separate variable/constant - ios

Question

I'm trying to set a variable/constant in Swift using a value from a function which finds the user's current location whilst the app is open. When I uncomment the print function it successfully prints the coordinates but I can't access the value outside of the function.
I currently have this as a part of my code which is in the MainVC.swift file as part of the MainVC class:
import UIKit
import MapKit
import CoreLocation
class MainVC: UIViewController, CLLocationManagerDelegate {
//Map
#IBOutlet weak var map: MKMapView!
let manager = CLLocationManager()
let coordinates = locationManager()
//I've also tried using let coordinates = currentCoords
override func viewDidLoad() {
super.viewDidLoad()
manager.delegate = self
manager.desiredAccuracy = kCLLocationAccuracyBest
manager.requestWhenInUseAuthorization()
manager.startUpdatingLocation()
}
func locationManager(_ manager: CLLocationManager, didUpdateLocations locations: [CLLocation]) -> String {
let location = locations[0]
let span:MKCoordinateSpan = MKCoordinateSpanMake(0.01, 0.01)
let myLocation:CLLocationCoordinate2D = CLLocationCoordinate2DMake(location.coordinate.latitude, location.coordinate.longitude)
let region:MKCoordinateRegion = MKCoordinateRegionMake(myLocation, span)
map.setRegion(region, animated: true)
lat = String(myLocation.latitude)
long = String(myLocation.longitude)
let currentCoords:String = "\(lat);\(long)"
//print(currentCoords)
self.map.showsUserLocation = true
return currentCoords
}
}
However I'm faced with this error:
"Cannot use instance member 'locationManager' within property initializer; property initializers run before 'self' is available".
When I change the code and use
let coordinates = currentCoords
I get another error showing:
"Use of unresolved identifier 'currentCoords'"
I have also tried using a lazy var and lazy let.

Answer 1

You should just be able to access locationManager.location?.coordinate as in my buttonClick method :
import UIKit
import MapKit
class ViewController: UIViewController,CLLocationManagerDelegate,MKMapViewDelegate {
let locationManager = CLLocationManager()
#IBAction func buttonClick(_ sender: Any) {
let location = locationManager.location?.coordinate
let lat:Double = (location?.latitude)!
let lon:Double = (location?.longitude)!
print(lat,lon)
}
#IBOutlet weak var mapView: MKMapView!
override func viewDidLoad() {
super.viewDidLoad()
mapView.delegate = self
mapView.showsUserLocation = true
mapView.userTrackingMode = .follow
locationManager.delegate = self
locationManager.distanceFilter = kCLLocationAccuracyNearestTenMeters
locationManager.desiredAccuracy = kCLLocationAccuracyBest
}
override func didReceiveMemoryWarning() {
super.didReceiveMemoryWarning()
// Dispose of any resources that can be recreated.
}
override func viewDidAppear(_ animated: Bool) {
super.viewDidAppear(animated)
print("viewDidAppear")
// status is not determined
if CLLocationManager.authorizationStatus() == .notDetermined {
locationManager.requestAlwaysAuthorization()
}
// authorization were denied
else if CLLocationManager.authorizationStatus() == .denied {
showAlert("Location services were previously denied. Please enable location services for this app in Settings.")
}
// we do have authorization
else if CLLocationManager.authorizationStatus() == .authorizedAlways {
locationManager.startUpdatingLocation()
}
}
func locationManager(_ manager: CLLocationManager, didUpdateLocations locations: [CLLocation]) {
print("didUpdateLocations")
print(locations.last?.coordinate)
}
func showAlert(_ title: String) {
let alert = UIAlertController(title: title, message: nil, preferredStyle: .alert)
alert.addAction(UIAlertAction(title: "Cancel", style: .default, handler: { (action) in
alert.dismiss(animated: true, completion: nil)
}))
self.present(alert, animated: true, completion: nil)
}
}

Answer 2

This is how you define your public variable
let coordinates:CLLocation = nil
Then in your didUpdateLocations assign the coordinates variable with last element of locations array. Then you'll have access to it everywhere.
Keep in mind didUpdateLocations may be called even up to a few seconds later so your public variable coordinates will be populated after may be up to a few seconds or so.
func coordinatesBecomeAvailable() {
// Here you can print your coordinates or start using them for the first time
}
func locationManager(_ manager: CLLocationManager, didUpdateLocations locations: [CLLocation]) {
let firstTime:Bool = (coordinates == nil)
coordinates = locations[0]
if (firstTime) // This is first time this function is called
coordinatesBecomeAvailable()
......
< Rest of your code here >
......
< This function does have any return value! no String nothing >
}
You just need to check whether the value of coordinates is nil or not.
Or you can check inside the didUpdateLocations whether this is the first time this delegate method is called.
This is not the most efficient and completed way of initializing and using location manager and I assume you just posted the code related to your problem.