Can't get directions from GoogleMaps because of "found nil" unrapping URL - swift

Question

I searched through this topic and found some codes I tried to implement into my project, but it won't work!
So, what do I wanna achieve?
I wanna have a button in the UI, and when user tap the button, the app displays directions to a specific point on the GoogleMap. But my function crashes on the URL.
This is my code:
func draw(src: CLLocationCoordinate2D, dst: CLLocationCoordinate2D){
let urlString = "https://maps.googleapis.com/maps/api/directions/json?origin=\(src)&destination=\(dst)&sensor=false&mode=driving&key=**API_KEY**" <- // Here I place API-Key
let url = URL(string: urlString) // Here is the crash!
URLSession.shared.dataTask(with: url!, completionHandler: {
(data, response, error) in
if(error != nil){
print("error")
}else{
do{
let json = try JSONSerialization.jsonObject(with: data!, options:.allowFragments) as! [String : AnyObject]
let routes = json["routes"] as! NSArray
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
let bounds = GMSCoordinateBounds(path: path!)
self.mapView!.animate(with: GMSCameraUpdate.fit(bounds, withPadding: 30.0))
polyline.map = self.mapView
}
})
}catch let error as NSError{
print("error:\(error)")
}
}
}).resume()
}
I don't know if the problem could be with the API-key, or if there's something else. I read that spaces etc could cause this issue, but I can't find what's wrong!
Error message:
Fatal error: Unexpectedly found nil while unwrapping an Optional value
2019-06-14 16:50:45 Fatal error: Unexpectedly found nil while unwrapping an Optional value

Answer 1

You wrongly create urlString with directly using CLLocationCoordinate2D as you have to use it's properties latitude/longitude
let urlString = "https://maps.googleapis.com/maps/api/directions/json?origin=\(src)&destination=\(dst)&sensor=false&mode=driving&key=**API_KEY**" <- // Here I place API-Key
it should be
let urlString = "https://maps.googleapis.com/maps/api/directions/json?origin=\(src.latitude),\(src.longitude)&destination=\(dst.latitude),\(dst.longitude)&sensor=false&mode=driving&key=**API_KEY**" <- // Here I place API-Key
Also it's better to avoid ! and do
guard let url = URL(string: urlString) else { return }