I think the most appropriate solution (without going too overboard, because there are certainly more thorough ways to go about this problem) is to separate the gps management into its own singleton class, and to subscribe to a trackerUpdated protocol for updates.
import Foundation
import placeWhereGPSTrackingManagerIs
protocol GPSManagerDelegate {
func didUpdateTracker(tracker: yourTrackerObject)
}
let _GPSManagerSharedInstance = GPSManager()
class GPSManager {
weak var delegate: GPSManagerDelegate?
let tracker: yourTrackerObject?
class var sharedInstance:GPSManager {
return _GPSManagerSharedInstance
}
init() {
tracker = GPSTrackingManager()
tracker.startUpdatingLocation()
}
func updateTracker(newInformation) // you'll want to pass whatever information your tracker needs here
{
tracker.trackerProperty = newInformation
self.delegate?.didUpdateTracker(tracker)
}
}
Swift singleton explanation
Using a dispatch_once singleton model in Swift
Now, whatever startUpdatingLocation does could call updateTracker in this class with the new information it needs to update the tracker. You could also migrate that logic to live inside of here (which I recommend doing in this case) so everything is contained in one class.
Any view controller interested in the information can subscribe to the didUpdateTracker protocol method, which will pass the tracker through to that view controller
import UIKit
class controllerOne: UIViewController, GPSManagerDelegate {
override func viewDidLoad() {
super.viewDidLoad()
GPSManager.sharedInstance.delegate = self // set the GPSManager delegate
if let tracker = GPSManager.sharedInstance.tracker {
// if the tracker exists, we assign it to the "tracker" variable, and use as needed
// setup page with tracker
}
}
func didUpdateTracker(updatedTracker: yourTrackerObject) {
// protocol method that will be called from the gpsmanager everytime it updates
// do whatever updates to the page with the
}
}
As you can only have one GPSManager and its tracker property cannot be changed, it is always safe to ask the GPS manager for this tracker, which only calls startUpdatingLocation() on its initialization
You could also post notifications as @shesh nath mentioned, which is a perfectly valid way to broadcast changes if you prefer it to the delegation method. Either way you approach it, I would recommend separating the tracker from the view controller so that the view controllers are not the ones in charge of managing the trackers state.
