Question

I was just curious what the correct way to draw a simple route line between a set of points was? I currently have an array of coordinates and when I pass it to polylineWithCoordinates and do all the other necessary things, it draws a big web of lines that interconnect all of the points to one another. I’ve looked at a few samples but none of them seem to do anything special to account for this, even when they use more than two points.

- (void)viewDidLoad
{
    [super viewDidLoad];

    ...

    //Add drawing of route line
    CLLocationCoordinate2D coordinates[[myCheckpoints count]];

    int i = 0;
    for (Checkpoint *ckpt in myCheckpoints)
    {
        coordinates[i] = CLLocationCoordinate2DMake([ckpt.lat floatValue] , [ckpt.lon floatValue]);
        i++;
    }

    MKPolyline *route = [MKPolyline polylineWithCoordinates: coordinates count: [myCheckpoints count]];
    [mapView addOverlay:route];

}

- (MKOverlayView *)mapView:(MKMapView *)mapView viewForOverlay:(id <MKOverlay>)overlay {

    MKPolylineView *polylineView = [[[MKPolylineView alloc] initWithPolyline:overlay] autorelease];
    polylineView.strokeColor = [UIColor greenColor];
    polylineView.lineWidth = 5.0;

    return polylineView;

}

This is the code in my mapViewController that is responsible for the drawing, just in case somebody sees what I’m doing, or not doing.

Now that I look at everything much closer, is actually not connecting adjacent coordinates to each other. Each point only has 2 lines stemming from it connecting that point to 2 more points but I cant figure out the pattern its connecting them in.

Answer 1

Make sure the coordinates in myCheckpoints are in the order that you want the lines drawn in.

It will draw the lines in the order the coordinates are provided.