Where should I instantiate a location manager if my app uses it throughout its various view controllers?

Question

I have an app that uses the user's location throughout its various view conrollers, and I've learned that in order to get that location you need to create a CLLocationManger instance and conform to the CLLocationManagerDelegate protocol.

Is it possible to make one CLLocationManager instance and use it's properties like coordinates in my different view controllers or should I make a CLLocationManager in each view controller class?

Answer 1

A quick and somewhat robust hack could be:

@UIApplicationMain
class AppDelegate: UIResponder, UIApplicationDelegate, CLLocationManagerDelegate {

    func application(application: UIApplication, didFinishLaunchingWithOptions launchOptions: [NSObject: AnyObject]?) -> Bool {
        locationManager = CLLocationManager()
        locationManager.delegate = self
        locationManager.startUpdatingLocation()
        return true
     }

    func locationManager(_ manager: CLLocationManager, didUpdateLocations locations: [CLLocation]) {
        lastLocation = locations.last!
    }

In this same source file, at global scope, add:

private var lastLocation: CLLocation? {
    didSet { 
        locationCallback?(lastLocation!)
        locationCallback = nil
    }
}

private var locationCallback: ((CLLocation) -> Void)?

func getLastLocation(callback: (CLLocationManager) -> Void) {
    guard let location = lastLocation else {
        locationCallback = callback
        return
     }
     locationCallback(location)
}

Finally, elsewhere in your app, you can get your last known location using just:

getLastLocation { location in
    print(location)
}