"didUpdateLocations" doesn't being called when monitoring significant location changes - ios

Question

I'm trying to monitor user's significant location changes using a singleton locationManager called LocationService, it goes like that:
LocationService.Swift:
class var sharedInstance: LocationService {
struct Static {
static var onceToken: dispatch_once_t = 0
static var instance: LocationService? = nil
}
dispatch_once(&Static.onceToken) {
Static.instance = LocationService()
}
return Static.instance!
}
var locationManager: CLLocationManager?
var location: CLLocation?
var delegate: LocationServiceDelegate?
override init() {
super.init()
self.locationManager = CLLocationManager()
guard let locationManager = self.locationManager else {
return
}
if CLLocationManager.authorizationStatus() == .NotDetermined {
locationManager.requestAlwaysAuthorization()
}
locationManager.delegate = self
locationManager.distanceFilter = 10
locationManager.desiredAccuracy = kCLLocationAccuracyBest
locationManager.pausesLocationUpdatesAutomatically = false
if NSString(string: UIDevice.currentDevice().systemName).floatValue >= 9 {
locationManager.allowsBackgroundLocationUpdates = true
}
}
func startUpdatingLocation() {
print("Starting Location Updates")
self.locationManager?.startUpdatingLocation()
}
func startMonitoringSignificantLocationChanges() {
print("Starting Significant Location Updates")
self.locationManager?.startMonitoringSignificantLocationChanges()
}
// CLLocationManagerDelegate
func locationManager(manager: CLLocationManager, didUpdateLocations locations: [CLLocation]) {
guard let location = locations.last else {
return
}
// singleton for get last location
self.location = location
}
myVC.swift:
private let locationService = LocationService.sharedInstance
func prepareInformation() {
self.locationService.delegate = self
self.locationService.startMonitoringSignificantLocationChanges()
}
but didUpdateLocations being called just one time when the app is launched, and then it doesn't even being called. But when I switch the line:
self.locationService.startMonitoringSignificantLocationChanges()
to:
self.locationService.startUpdatingLocation()
it works great and called every time the user moves.
what can be the problem? Thank you!

Answer 1

According to Apple docs
After returning a current location fix, the receiver generates update
events only when a significant change in the user’s location is
detected. It does not rely on the value in the distanceFilter property
to generate events.
And
Apps can expect a notification as soon as the device moves 500 meters
or more from its previous notification. It should not expect
notifications more frequently than once every five minutes. If the
device is able to retrieve data from the network, the location manager
is much more likely to deliver notifications in a timely manner
I think you are expecting an event when the user changes its location by 10 meters, but this method doesn't depend on distanceFilter. Whoever when you use startUpdatingLocation() you will get events which will depend on distanceFilter property.
You can read more about this here.