Not able to draw Polyline Google Maps : Swift 3

Question

I am trying to draw route between two points but not able to do so beacuese there is nill value in my polypoints. This is how I am doing it :

Parsing JSON :

if let json : [String:Any] = try JSONSerialization.jsonObject(with: data!, options: .allowFragments) as? [String: Any]{

                        if let routes = json["routes"] as? [Any]{
                            if let overview_polyline = routes[0] as?[String:Any]{
                                print("overview_polyline\(overview_polyline)")// Getting values till here
                                if let polyString = overview_polyline["points"] as? String{

                                    //Call this method to draw path on map
                                    self.showPath(polyStr: polyString)
                                }

                            }
                        }
                    }

Till polystring I am getting values but not getting any value for this line of code if let polyString = overview_polyline["points"] as? String. Any idea why polyString is nil ?

I have gone through this link to clear the concepts still not able to implement it. unexpectedly found nil while unwrapping an Optional value

Answer 1

I achieved this by modifying above code to this code. So to parse google api and create a polyline on map, you can use this code, written in swift 3.

if let json : [String:Any] = try JSONSerialization.jsonObject(with: data!, options: .allowFragments) as? [String: Any]{
      let routes = json["routes"] as! NSArray;
      print(routes)
      self.mapView.clear()
      OperationQueue.main.addOperation({
          for route in routes {
                let routeOverviewPolyline:NSDictionary = (route as! NSDictionary).value(forKey: "overview_polyline") as! NSDictionary
                let points = routeOverviewPolyline.object(forKey: "points")
                let path = GMSPath.init(fromEncodedPath: points! as! String)
                let polyline = GMSPolyline.init(path: path)
                polyline.strokeWidth = 3
                polyline.map = self.mapView
           }
       })
}