NSString *urlString = [NSString stringWithFormat:
@"%@?origin=%f,%f&destination=%f,%f&sensor=true&key=%@",
@"https://maps.googleapis.com/maps/api/directions/json",
mapView.myLocation.coordinate.latitude,
mapView.myLocation.coordinate.longitude,
destLatitude,
destLongitude,
@"Your Google Api Key String"];
NSURL *directionsURL = [NSURL URLWithString:urlString];
ASIHTTPRequest *request = [ASIHTTPRequest requestWithURL:directionsURL];
[request startSynchronous];
NSError *error = [request error];
if (!error) {
NSString *response = [request responseString];
NSLog(@"%@",response);
NSDictionary *json =[NSJSONSerialization JSONObjectWithData:[request responseData] options:NSJSONReadingMutableContainers error:&error];
GMSPath *path =[GMSPath pathFromEncodedPath:json[@"routes"][0][@"overview_polyline"][@"points"]];
GMSPolyline *singleLine = [GMSPolyline polylineWithPath:path];
singleLine.strokeWidth = 7;
singleLine.strokeColor = [UIColor greenColor];
singleLine.map = self.mapView;
}
else NSLog(@"%@",[request error]);
Note: make Sure Your Google Direction API Sdk Is Enable in Your google developer Console.