Overlaying multiple polygons on the mapView-iOS

Question

As you seen in the image, there are numbers of polygon on the top of the mapView. Each polygon overlays on the top of other polygon. This causes opacity problem and that misleads user to interpret colors by referring to colormap.

Before placing any polygons, first I want to remove/clear the new polygon area then add the polygon.

I hope my question clear! if not, please let me know. Appreciated in advance.

I have also add portion of my code below as a reference! Polygon data comes from server in JSON format and I get coordinates out of this data and add them as a polygon for each time stamp.

for(bb = 0; bb < [polygonArray count]; bb++){
        coords = malloc(sizeof(CLLocationCoordinate2D) * [[polygonArray objectAtIndex:bb] count]);
        for (int a = 0;a < [[polygonArray objectAtIndex:bb] count]; a++){
            coords[a].latitude = [[[[polygonArray objectAtIndex:bb]objectAtIndex:a]objectAtIndex:0]doubleValue];
            coords[a].longitude = [[[[polygonArray objectAtIndex:bb]objectAtIndex:a]objectAtIndex:1]doubleValue];
        }
        polygon = [[MKPolygon alloc]init];
        polygon = [MKPolygon polygonWithCoordinates:coords count:[[polygonArray objectAtIndex:bb]count]];
        [previousPolygons addObject:polygon];
        [mapView addOverlay:polygon];
        }

    }

enter image description here

score 0 · Answer 1 · answered Dec 05 '12 at 03:12

Hmm. I'm a little unclear on what you want to do. If you simply want to remove a polygon, you'd have to some how find the polygon you want remove and run

[mapView removeOverlay:polygon]

If you want to remove all polygons then you could run

[mapView removeOverlays:mapView.overlays]

Overlaying multiple polygons on the mapView-iOS

1 Answers1