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 ?

I think Google does not know how to reach to the destination, because of there is no route, or there is in private area, something like that. — wf9a5m75, Jan 11 '16 at 23:54

score 5 · Accepted Answer · answered Jan 14 '16 at 05:07

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.

score 1 · Answer 2 · edited May 23 '17 at 12:22

1

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

edited May 23 '17 at 12:22

Community

1
1

answered Jan 14 '16 at 02:59

Stefano Saitta

1,844
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Well if that is true then why Google maps show the path correctly on [**web**](https://www.google.co.in/maps/dir/Vju+AS,+Skreddermoen+35,+4513+Mandal,+Norway/Storgata+2,+0155+Oslo,+Norway/@59.9082978,10.7358573,13z/data=!4m14!4m13!1m5!1m1!1s0x46378e55431b5435:0x306f6da1490b5f7b!2m2!1d7.4111312!2d58.0184825!1m5!1m1!1s0x46416e627216c757:0xd7785d6e9ecf2c43!2m2!1d10.7483587!2d59.9127025!3e0?hl=en) ? – Nitish Jan 14 '16 at 04:57

Google map SDK - Path not accurate

2 Answers2