How stop locationManagerUpdates from ViewController in applicationDidEnterBackground - ios

Question

I need stop locationUpdates from AppDelegate when applicationDidEnterBackground , and startUpdatingLocation when applicationDidBecomeActive from ViewController, here is my Code..
How can do it if my locationManager is in the ViewController.
import CoreLocation
class ViewController: UIViewController, CLLocationManagerDelegate
var seenError : Bool = false
var locationFixAchieved : Bool = false
var locationStatus : NSString = "Not Started"
var locationManager: CLLocationManager!
override func viewDidLoad() {
super.viewDidLoad()
}
func initLocationManager() {
seenError = false
locationFixAchieved = false
locationManager = CLLocationManager()
locationManager.delegate = self
locationManager.locationServicesEnabled
locationManager.desiredAccuracy = kCLLocationAccuracyBest
locationManager.requestAlwaysAuthorization()
}
func locationManager(manager: CLLocationManager!, didFailWithError error: NSError!) {
locationManager.stopUpdatingLocation()
if (error) {
if (seenError == false) {
seenError = true
print(error)
}
}
}
func locationManager(manager: CLLocationManager!, didUpdateLocations locations: AnyObject[]!) {
if (locationFixAchieved == false) {
locationFixAchieved = true
var locationArray = locations as NSArray
var locationObj = locationArray.lastObject as CLLocation
var coord = locationObj.coordinate
println(coord.latitude)
println(coord.longitude)
}
}
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
}
NSNotificationCenter.defaultCenter().postNotificationName("LabelHasbeenUpdated", object: nil)
if (shouldIAllow == true) {
NSLog("Location to Allowed")
// Start location services
locationManager.startUpdatingLocation()
} else {
NSLog("Denied access: \(locationStatus)")
}
}

Answer 1

NSNotificationCenter is a simple way to send messages within your application. Each class which needs to respond to such messages registers an observer to listen for the message.
AppDelegate:
func applicationDidEnterBackground(application: UIApplication) {
// Send a message that informs all listening classes for entering background
NSNotificationCenter.defaultCenter().postNotification(NSNotification(name: "appEntersBackground", object: nil))
}
func applicationDidBecomeActive(application: UIApplication) {
// Send a message that informs all listening classes for becoming active again
NSNotificationCenter.defaultCenter().postNotification(NSNotification(name: "appBecomesActive", object: nil))
}
Swift 4.2
NotificationCenter.default.post(name: Notification.Name("appEntersBackground"), object: nil)
ViewController
In your viewController, register observers for the messages:
class ViewController: UIViewController, CLLocationManagerDelegate {
...
override func viewDidLoad() {
super.viewDidLoad()
// register observers
NSNotificationCenter.defaultCenter().addObserver(self, selector: "enterBackground", name: "appEntersBackground", object: nil)
NSNotificationCenter.defaultCenter().addObserver(self, selector: "becomeActive", name: "appBecomesActive", object: nil)
}
deinit {
// remove observers
NSNotificationCenter.defaultCenter().removeObserver(self)
}
// app enters background
func enterBackground() {
self.locationManager.stopUpdatingLocation()
}
// app becomes active
func becomeActive() {
self.locationManager.startUpdatingLocation()
}
}
Swift 4.2
NotificationCenter.default.addObserver(self, selector: #selector(enterBackground), name: Notification.Name("appEntersBackground"), object: nil)
#objc func enterBackground() {
self.locationManager.stopUpdatingLocation()
}
Note that the locationmanager stops updating locations in background unless you have registered your app for background tasks in Info.plist.

Answer 2

You can fire notifications startUpdatingLocation from applicationDidBecomeActive and stopUpdatingLocation from applicationDidEnterBackground. Then you can listen to these notifications in your view controller to manage locationManager.

Answer 3

You can use this code-
func applicationDidEnterBackground(application: UIApplication) {
self.locationManager.stopUpdatingLocation()
}
func applicationDidBecomeActive(application: UIApplication) {
self.locationManager.startUpdatingLocation()
}
One more suggestion, you can put a check in your initLocationManager method -
if (self.locationManager.respondsToSelector(Selector("requestAlwaysAuthorization"))) {
self.locationManager.requestAlwaysAuthorization()
}