Remove a polyLine from the mapView - ios

Question

I've read many posts about it and still i have a problem.
This is my code to draw a polyLine between two points:
-(void) drawAline:(CLLocation*)newLocation
{
//drawing a line
CLLocationCoordinate2D coordinateArray[2];
coordinateArray[0] = CLLocationCoordinate2DMake(newLocation.coordinate.latitude, newLocation.coordinate.longitude);
coordinateArray[1] = CLLocationCoordinate2DMake(self.jerusalem.coordinate.latitude, self.jerusalem.coordinate.longitude);
self.routeLine = [MKPolyline polylineWithCoordinates:coordinateArray count:2];
[self.mapView setVisibleMapRect:[self.routeLine boundingMapRect]];
[self.mapView addOverlay:self.routeLine];
}
-(MKOverlayView *)mapView:(MKMapView *)mapView viewForOverlay:(id<MKOverlay>)overlay
{
if(overlay == self.routeLine)
{
if(nil == self.routeLineView)
{
self.routeLineView = [[MKPolylineView alloc] initWithPolyline:self.routeLine];
self.routeLineView.fillColor = [UIColor blueColor];
self.routeLineView.strokeColor = [UIColor blueColor];
self.routeLineView.lineWidth = 5;
}
return self.routeLineView;
}
return nil;
}
thats works fine.
The problem is to remove the line.
The next code doesn't work:
for (id<MKOverlay> overlayToRemove in self.mapView.overlays)
{
if ([overlayToRemove isKindOfClass:[MKPolylineView class]])
{
[mapView removeOverlay:overlayToRemove];
}
}
the next code doesn't work neither:
if (self.routeLine)
{
[self.mapView removeOverlay:self.routeLine];
self.routeLineView = nil;
self.routeLine = nil;
}
Thanks!

Answer 1

In the code that loops through the map view's overlays array, this line is the problem:
if ([overlayToRemove isKindOfClass:[MKPolylineView class]])
The map view's overlays array contains objects of type id<MKOverlay> (the for-loop correctly declares overlayToRemove as such).
So the overlays array contains the model objects for the overlays and not the views.
The MKPolylineView class is the view for an MKPolyline overlay model.
So the if condition should be:
if ([overlayToRemove isKindOfClass:[MKPolyline class]])
Note that such a loop will remove all polylines from the map. If you wanted to delete specific polylines, you could set the title on each one when adding it and then check it before removing.
The second piece of code that checks and deletes self.routeLine directly should work as long as self.routeLine is not nil and contains a valid reference to an overlay currently on the map.
If you have only a single overlay on the map (the one polyline), you could also just call removeOverlays to delete all overlays from the map (whatever they are):
[self.mapView removeOverlays:self.mapView.overlays];

Answer 2

Your overlay is a MKPolyline the MKPolylineView is just how the overlay is displayed when the map is zoomed or scrolled so that the overlay's data shows in the window. The map view's overlays array contains the data that will be used to generate the overlay views. There are no views in the overlays array. So, to make your code work, change this line
if ([overlayToRemove isKindOfClass:[MKPolylineView class]])
to
if ([overlayToRemove isKindOfClass:[MKPolyline class]])
in your third snippet and you will be fine