Google Maps decoded GMSPath incorrect iOS - ios

Question

So, I use the directions API in my app. However, when I decode the polyline from the response, it does not show up correctly. Here is my code:
//Construct request URL
NSString *urlString = [NSString stringWithFormat:
#"%#?origin=%f,%f&destination=%f,%f&sensor=true&key=%#",
#"https://maps.googleapis.com/maps/api/directions/json",
userMarker.position.latitude,
userMarker.position.longitude,
place.coordinate.latitude,
place.coordinate.longitude,
#"AIzaSyDrtHA-AMiVVylUPcp46_Vf1eZJJFBwRCY"];
NSURL *directionsURL = [NSURL URLWithString:urlString];
//Get directions in JSON format
dispatch_async(dispatch_get_main_queue(), ^{
NSData* data = [NSData dataWithContentsOfURL:directionsURL];
NSError* error;
if(data){
NSDictionary *json = [NSJSONSerialization JSONObjectWithData:data options:kNilOptions error:&error];
//Parse JSON and plot route on map
NSDictionary *routes = [json objectForKey:#"routes"][0];
NSDictionary *route = [routes objectForKey:#"overview_polyline"];
NSString *overview_route = [route objectForKey:#"points"];
//Clear map from previous polylines
[self.mapView clear];
//Make polyline
GMSPath *path = [GMSPath pathFromEncodedPath:overview_route];
GMSPolyline *polyline = [GMSPolyline polylineWithPath:path];
polyline.strokeWidth = 4;
polyline.strokeColor = [UIColor darkGrayColor];
polyline.map = self.mapView;
});
And here is the polyline:
As you can,see it does not follow the road properly. However, to me it seems as if there are not enough points to have proper bends.
EDIT: This only happens 50% of the time, sometimes it shows up correctly, sometimes it does not.
What could I be doing wrong?

Answer 1

Going by this (which is using the js API instead of the json API that you're using):
Get a polyline from Google maps directions V3
It looks like you should use the lines in each of the steps of the legs in the response, instead of the overview_polyline which is probably meant to be just a rough approximate line.