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LocationManager: didUpdateLocations: always called multiple times

I start updating the current location when the view appears and stop updating the location whenever called locationManager:didUpdateLocations:. But why is it locationManager:didUpdateLocations:always called several times? What did I miss?

#import "ViewController.h"

@interface ViewController (){
    CLLocationManager *locationManager; // location manager for current location
}
@end

@implementation ViewController
- (void)viewDidLoad
{
    [super viewDidLoad];
}

- (void)viewDidAppear:(BOOL)animated
{
    [super viewDidAppear:animated];
    [self startUpdatingCurrentLocation];
}

- (void)startUpdatingCurrentLocation
{
    if (!locationManager)
    {
        locationManager = [[CLLocationManager alloc] init];
        [locationManager setDelegate:self];
        locationManager.distanceFilter = 10.0f; // we don't need to be any more accurate than 10m
    }
    [locationManager startUpdatingLocation];
}

-(void)locationManager:(CLLocationManager *)manager didUpdateLocations:(NSArray *)locations{
    [locationManager stopUpdatingLocation];
}
@end
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3 answers

This probably depends on the accuracy you set in the locationManager. You have 3 types o localization of Cell Radio, WiFi Map, GPS. If you are in the best position, the location manager will continue to check your position, if the location with better accuracy goes beyond the distance filter, the delegate method will be called again.

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SWIFT version

i HelperLocationManager notification- observer

import UIKit
import CoreLocation



class HelperLocationManager: NSObject {

    var locationManager = CLLocationManager()
    static let sharedInstance = HelperLocationManager()
    var currentLocation :CLLocation?
    var notGotUserLocation = true

    override init() {

        super.init()

        var code = CLLocationManager.authorizationStatus()

        if code == CLAuthorizationStatus.NotDetermined {

            locationManager.requestAlwaysAuthorization()
            locationManager.requestWhenInUseAuthorization()

        }
        locationManager.requestAlwaysAuthorization()
        locationManager.requestWhenInUseAuthorization()
        locationManager.delegate = self
        locationManager.distanceFilter = 100;

    }


}


extension HelperLocationManager: CLLocationManagerDelegate{


    func locationManager(manager: CLLocationManager!, didUpdateLocations locations: [AnyObject]!) {

            var locValue = locations.last as! CLLocation
            println(locValue)
            self.currentLocation = locValue
            NSNotificationCenter.defaultCenter().postNotificationName("sendCurrentAddressToViewController", object:self.currentLocation)
            notGotUserLocation = false


    }

    func locationManager(manager: CLLocationManager!, didFailWithError error: NSError!) {

        println("Your error is ", error.localizedDescription)

    }


}

, Viewcontroller ,

var helperLocation:HelperLocationManager?

viewDidLoad

     override func viewDidLoad() {

         helperLocation = HelperLocationManager()
         NSNotificationCenter.defaultCenter().addObserver(self, selector: "getCurrentAddressToViewController:", name: "sendCurrentAddressToViewController", object: nil)

  }

//

 func getCurrentAddressToViewController(notification: NSNotification) {

        currentLocation = notification.object as? CLLocation
        NSNotificationCenter.defaultCenter().removeObserver(self, name: "sendCurrentAddressToViewController", object: nil)

    }

// didUpdateLocation , - observer , .

: -, .

class HelperLocationManager: NSObject {

    private lazy var locationManager = CLLocationManager()
    static let sharedInstance = HelperLocationManager()
    var currentLocation :CLLocation?

    override init() {

        super.init()
        locationManager.desiredAccuracy = kCLLocationAccuracyBest
        locationManager.delegate = self
    }
}

extension HelperLocationManager: CLLocationManagerDelegate{

    func locationManager(manager: CLLocationManager, didChangeAuthorizationStatus status: CLAuthorizationStatus) {

        switch status {

        case CLAuthorizationStatus.NotDetermined:

            locationManager.requestWhenInUseAuthorization()


        case CLAuthorizationStatus.Restricted:

            PrinterHelper.messagePrinter("Restricted Access to location")

        case CLAuthorizationStatus.Denied:

            PrinterHelper.messagePrinter("User denied access to location")

        case CLAuthorizationStatus.AuthorizedWhenInUse:

            if #available(iOS 9.0, *) {

                locationManager.requestLocation()

            } else {

                locationManager.startUpdatingLocation()
            }

        default:

            PrinterHelper.messagePrinter("default authorization")

        }
    }

    func locationManager(manager: CLLocationManager, didUpdateLocations locations: [CLLocation]) {

        let locValue = locations.last
        HelperLocationManager.sharedInstance.currentLocation =  locValue
        locationManager.stopUpdatingLocation()

    }

    func locationManager(manager: CLLocationManager, didFailWithError error: NSError) {

        PrinterHelper.errorPrinter(error.localizedDescription)

    }
}

,

var helperLocationManager:HelperLocationManager?

viewDidLoad

     override func viewDidLoad() {

         helperLocationManager = HelperLocationManager.sharedInstance


  }

, singleton currentLocation

 if  let userCurentLoc = HelperLocationManager.sharedInstance.currentLocation{

           //userCurrentLoc is the user Location

        }
+3

In addition to Anish's answer, if you want to know when your helper class did not cause the location update (i.e. when you turned off location services), you can control this using the method locationManager:didChangeAuthorizationStatus:, and if your location is not allowed, you can call to anothernotification- observer

func locationManager(manager: CLLocationManager, didChangeAuthorizationStatus status: CLAuthorizationStatus) {
    var shouldIAllow = false

    switch status {
    case CLAuthorizationStatus.Restricted:
        locationStatus = "Restricted Access to location"
    case CLAuthorizationStatus.Denied:
        locationStatus = "User denied access to location"
    case CLAuthorizationStatus.NotDetermined:
        locationStatus = "Status not determined"
    default:
        locationStatus = "Allowed to location Access"
        shouldIAllow = true
    }

    if (shouldIAllow == true) {
        print("Location to Allowed")
        // Start location services
        locationManager!.startUpdatingLocation()
    } else {
        print("Denied access: \(locationStatus)")
        NSNotificationCenter.defaultCenter().postNotificationName("deniedLocation", object:locationStatus)
    }
}
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