Swift iOS google Map, path to coordinate

Question

I am trying to create a function in my app that will guide the user to a marker I have created. This is the code I am using, it works great, It gets the users current location and show it on the map. But how can I get a directions to a marker?

Any awnser will be helpful

class Karta: UIViewController, CLLocationManagerDelegate {
    @IBOutlet var mapView: GMSMapView!

    let locationManager = CLLocationManager()

    override func viewDidLoad() {
        super.viewDidLoad()

        //allow app to track user
        locationManager.delegate = self
        locationManager.requestWhenInUseAuthorization()

        //set out a marker on the map
        var marker = GMSMarker()
        marker.position = CLLocationCoordinate2DMake(56.675907, 12.858798)
        marker.appearAnimation = kGMSMarkerAnimationPop
        marker.icon = UIImage(named: "flag_icon")
        marker.map = mapView
     }

    override func prepareForSegue(segue: UIStoryboardSegue, sender: AnyObject?) {
        if segue.identifier == "Types Segue" {
            let navigationController = segue.destinationViewController as UINavigationController
        }
    }

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

        //If map is being used
        if status == .AuthorizedWhenInUse {
            var myLocation = mapView
            locationManager.startUpdatingLocation()
            mapView.myLocationEnabled = true
            mapView.settings.myLocationButton = true
        }
    }

    func locationManager(manager: CLLocationManager!, didUpdateLocations locations: [AnyObject]!) {
        if let location = locations.first as? CLLocation {
            mapView.camera = GMSCameraPosition(target: location.coordinate, zoom: 15, bearing: 0, viewingAngle: 0)
          locationManager.stopUpdatingLocation()
        }
    }
}

Answer 1

So i recently just solved this issue, here is my Swift 3 implementation using the latest version of Alamofire (4.3)

 func fetchMapData() { 

    let directionURL = "https://maps.googleapis.com/maps/api/directions/json?" +
        "origin=\(originAddressLat),\(originAddressLng)&destination=\(destinationAddressLat),\(destinationAddressLong)&" +
    "key=YOUROWNSERVERKEY"



    Alamofire.request(directionURL).responseJSON
        { response in

            if let JSON = response.result.value {

                let mapResponse: [String: AnyObject] = JSON as! [String : AnyObject]

                let routesArray = (mapResponse["routes"] as? Array) ?? []

                let routes = (routesArray.first as? Dictionary<String, AnyObject>) ?? [:]

                let overviewPolyline = (routes["overview_polyline"] as? Dictionary<String,AnyObject>) ?? [:]
                let polypoints = (overviewPolyline["points"] as? String) ?? ""
                let line  = polypoints

                self.addPolyLine(encodedString: line)
        }
    }

}

func addPolyLine(encodedString: String) {

    let path = GMSMutablePath(fromEncodedPath: encodedString)
    let polyline = GMSPolyline(path: path)
    polyline.strokeWidth = 5
    polyline.strokeColor = .blue
    polyline.map = whateverYourMapViewObjectIsCalled

}