Google map SDK - Path not accurate

Question

I am trying to show path between two locations but it is not accurate.

if(center.latitude != 0 && center.longitude != 0)
            {
            NSString *urlString = [NSString stringWithFormat:
                                   @"%@?origin=%f,%f&destination=%f,%f&sensor=true&key=%@",
                                   @"https://maps.googleapis.com/maps/api/directions/json",
                                   center.latitude,
                                   center.longitude,
                                   center1.latitude,
                                   center1.longitude,
                                   KGoogleMapServerKey];

            NSError *error;
                NSDictionary *json =[NSJSONSerialization JSONObjectWithData:[NSData dataWithContentsOfURL:[NSURL URLWithString:urlString] options:NSDataReadingUncached error:&error] options:NSJSONReadingMutableContainers error:&error];
            if(json[@"routes"] != nil && [json[@"routes"] count] > 0)
            {
                GMSPath *path =[GMSPath pathFromEncodedPath:json[@"routes"][0][@"overview_polyline"][@"points"]];
                GMSPolyline *singleLine = [GMSPolyline polylineWithPath:path];
                singleLine.strokeWidth = 7;
                singleLine.strokeColor = [UIColor colorWithRed:56.0/255.0 green:163.0/255.0 blue:249.0/255.0 alpha:1.0];
                singleLine.map = mapViewGoogle;
            }  

This is the path I am getting :

As you can see, the blue line (path) does not go at the destination.
How to fix this ?

Answer 1

Your route is too long. In each response from Google Directions API number of points is limited. In your example you received N points, drew route with them and zoomed mapView to area, where only four points placed.
To display always accurate route you should after each map zooming re-calculate route (including midpoints to keep route the same).
For example, full route on your screen has 50 points. You are zooming the map, so only 4 points displayed (your screenshot). Now take #1 as start, #5 as finish and #2 #3 #4 as midpoints and send new request to find route for these points. You'll receive new 50 points, and with them you can draw this part of route more accurately.

Answer 2

The point of this is that there is no route for that destination, as you can see here : Gmap of your Example

I guess that your best bet is use the same approach that Gmaps already use, i mean using dotted/dashed polyline from the last point you get directions to the actual point.

You can find out here couple examples of out to implement thy type of polyline:

Creating a dashed using IOS SDK