func calculateRoutes(from f: CLLocationCoordinate2D, to t: CLLocationCoordinate2D)  {

    let saddr = "(f.latitude),(f.longitude)"
    let daddr = "(t.latitude),(t.longitude)"

    let url = "https://maps.googleapis.com/maps/api/directions/json?origin=(saddr)&destination=(daddr)&sensor=false&mode=driving&key=(googleApiKey)"

    Alamofire.request(url).responseJSON { response in

        do {
            let json = try JSONSerialization.jsonObject(with: response.data!, options: .mutableContainers) as! NSDictionary

            let routes = (json.object(forKey: "routes") as! NSArray)

            if routes.count > 0 {

                if let route = ((routes.object(at: 0) as? NSDictionary)?.object(forKey: "overview_polyline") as? NSDictionary)?.value(forKey: "points") as? String {

                    self.mapview.clear()

                    let path  = GMSPath(fromEncodedPath:route)!
                    let polyline  = GMSPolyline(path: path)
                    polyline.strokeColor = UIColor.black
                    polyline.strokeWidth = 5.0
                    polyline.map = self.mapview

                }

            }

        } catch {
        }

    }
}