mapView.showsUserLocation = true affects the correctness of gps in my swift app. Why? - ios

Question

In my app I want to know user's real location. I want to show it in couple places as a plain text (as a string of longitude/latitude) and also show it on the map. I have several ui view controllers and one of them contains - now, for testing - a print to the console with current longitude and latitude, it also contains a map view.
I'm fetching the current gps position from my app delegate and put it on the screen.
In my AppDelegate.swift class I have:
var locationManager: CLLocationManager! = nil
var location: CLLocation! = nil
var longitude : Double = 0
var latitude : Double = 0
var location_fixed = false
func application(application: UIApplication,
didFinishLaunchingWithOptions launchOptions: [NSObject: AnyObject]?) -> Bool {
initLocationManager()
}
func initLocationManager() {
locationManager = CLLocationManager()
locationManager.delegate = self
locationManager.desiredAccuracy = kCLLocationAccuracyBest
if CLLocationManager.authorizationStatus() == .AuthorizedAlways {
locationManager!.startUpdatingLocation()
} else {
locationManager!.requestAlwaysAuthorization()
}
}
func locationManager(manager: CLLocationManager, didFailWithError error: NSError) {
print("Failed to initialize GPS: ", error.description)
}
func locationManager(manager: CLLocationManager, didUpdateLocations locations: [CLLocation]) {
location = locations.first!
print("Managed to get a fix on location")
let coord = location.coordinate
longitude = coord.longitude
latitude = coord.latitude
location_fixed = true;
locationManager.stopUpdatingLocation()
}
func locationManager(manager: CLLocationManager, didChangeAuthorizationStatus status: CLAuthorizationStatus) {
switch status {
case .NotDetermined:
print("NotDetermined")
case .Restricted:
print("Restricted")
case .Denied:
print("Denied")
case .AuthorizedAlways:
print("AuthorizedAlways")
locationManager!.startUpdatingLocation()
case .AuthorizedWhenInUse:
print("AuthorizedWhenInUse")
locationManager!.startUpdatingLocation()
}
}
func stopGPS() -> Void
{
print("STOP GPS")
location_fixed = false;
locationManager.stopUpdatingLocation()
}
func startGPS() -> Void
{
locationManager.startUpdatingLocation()
}
func isLocationFixed() -> Bool
{
return self.location_fixed
}
func getLongitude() -> Double
{
return self.longitude
}
func getLatitude() -> Double
{
return self.latitude
}
func getLocation() -> CLLocation
{
return self.location
}
Now in my UIViewController in viewWillAppear method I added asynchronous call to the app delegate methods for checking current gps position:
let priority = DISPATCH_QUEUE_PRIORITY_DEFAULT
dispatch_async(dispatch_get_global_queue(priority, 0)) {
let appDelegate = UIApplication.sharedApplication().delegate as! AppDelegate
appDelegate.startGPS()
while (!appDelegate.isLocationFixed())
{
sleep(1)
}
dispatch_async(dispatch_get_main_queue()) {
self.fetchRequests(self.radius, lat: appDelegate.getLatitude(), lon: appDelegate.getLongitude())
print("gps here: \(appDelegate.getLatitude()), \(appDelegate.getLongitude())") }
}
and now when I enter this panel and waits for fetching the gps - I see the correct data. So far so good. Now, when I change the gps position in a simulator, then go to some other panel and come back to this one - I see the new data, which is fine.
And now comes the real weird problem. In the same panel I have a map view.
It's embedded in a UIViewController that I put in a container, so I cannot access it from my async call. It has a viewDidLoad() method and when I put there:
mapView.showsUserLocation = true
and run the app, I see the blue dot exactly when the simulator's gps points out, but now my data in the previous async call is not updating correctly.
When I comment out that one particular line of code, I'm getting the correct data shown as gps here:. When I leave it as a part of the code, then this line gps here: shows the same data all the time, even though I'm changing the gps position in a simulator, leaving and entering the panel several times. What's up with that?