Swift CLLocation does not update location at startup - ios

Question

I have an application were I want to get the users location in viewDidLoad, I then store the lat and long in variables and use them in a function to get data based on the position from the user. I have a timer that calls a function every x minute that gets data (let´s call it getData()), the first time getData() is called lat and long is 0, but the second, third time etc.. they have values.
When I update the coords (during runtime) in the simulator I do get the updated values for both lat and long, but it´s the first run that lat and long always are 0. My code looks like this:
let locationManager = CLLocationManager()
var getDataGroup = dispatch_group_create()
override func viewDidLoad() {
super.viewDidLoad()
dispatch_group_enter(getDataGroup)
self.locationManager.delegate = self
self.locationManager.desiredAccuracy = kCLLocationAccuracyBest
self.locationManager.requestWhenInUseAuthorization()
self.locationManager.startUpdatingLocation()
dispatch_group_leave(getDataGroup)
dispatch_group_wait(getDataGroup, DISPATCH_TIME_FOREVER)
dispatch_async(dispatch_get_main_queue()) {
self.getData()
}
}
func locationManager(manager: CLLocationManager!, didUpdateLocations locations: [AnyObject]!) {
CLGeocoder().reverseGeocodeLocation(manager.location, completionHandler: { (placemarks, error) -> Void in
if (error != nil){
println("Error: " + error.localizedDescription)
return
}
if (placemarks.count > 0){
let pm = placemarks[0] as! CLPlacemark
self.displayLocationInfo(pm)
}
else{
println("Error with location data")
}
})
}
func displayLocationInfo (placemark : CLPlacemark){
self.locationManager.stopUpdatingLocation()
lat = String(stringInterpolationSegment: placemark.location.coordinate.latitude)
long = String(stringInterpolationSegment: placemark.location.coordinate.longitude)
}
func locationManager(manager: CLLocationManager!, didFailWithError error: NSError!) {
println("Error: " + error.localizedDescription)
}
func getData(){
// Do stuff with lat and long...
}
For some reason the first run lat and long are both 0, the rest of the runs they have a valid value. The problem is that getData is called before the locationManager and displayLocationInfo methods even though I have added self.locationManager.startUpdatingLocation() before the call to getData() for some reason.

Answer 1

I don't really understand what your code is supposed to do.
There's no reason for the GCD code in your viewDidLoad. simply create an instance of the location manager and tell it to start updating your location.
Then your didUpdateLocations method will be called once a location is available. Use the last location in the array of locations you get in that method - it will be the most recent.
I would advise checking the horizontalAccuracy of the locations before using them. Typically the first few location readings are really bad, and then slowly the readings settle down. The Horizontal accuracy reading is actually a radius giving the possible area of the reading. If you get 1 km, it means your location could be anywhere in a circle 1 km in radius. You probably want to discard readings that bad and wait for one that's within a few hundred meters (or better.)
Your viewDidLoad method is calling a method getDeparturesAtStop, and that method will likely be called before the first call to didUpdateLocations fires. (You don't show what that method does.)
Where is the code that is getting a zero lat/long?