MKPolygonRenderer - tough memory issues - objective-c

Question

i am currently facing a hard memory issue while using the new iOS7 MKPolygonRenderer class.. I pinpointed the source of the issue to a single line of code:
[renderer invalidatePath];
it seems like the core framework is not releasing the memory here, so that subsequent calls to this function result in an application crash due to memory exceptions.
basically what i want to do is to let the user alter a single polygon overlay on the map.
#interface MapViewController () <MKMapViewDelegate>
{
MKPolygonRenderer* renderer;
}
#end
#implementation MapViewController
- (id) init
{
if ((self=[super init]) != nil)
{
MKMapView* viewMap = [[MKMapView alloc] initWithFrame:CGRectMake(0, 0, self.view.frame.size.width, self.view.frame.size.height)];
viewMap.autoresizingMask = UIViewAutoresizingFlexibleWidth | UIViewAutoresizingFlexibleHeight;
viewMap.delegate = self;
[self.view addSubview:viewMap];
viewMap.region = MKCoordinateRegionMake(CLLocationCoordinate2DMake(49.391759,8.675766), MKCoordinateSpanMake(0.35, 0.35));
// a simple polygon overlay with 4 points
CLLocationCoordinate2D overlayCoords[4] = { {49.421247,8.607101}, {49.418121,8.745117}, {49.321094,8.734818}, {49.320199,8.613968}/*, {49.370199,8.583968} */};
MKPolygon* overlay = [MKPolygon polygonWithCoordinates:overlayCoords count:4];
[viewMap addOverlay:overlay];
// the gesture recognizer which is used to alter the polygon
UILongPressGestureRecognizer* longPressRecognizer = [[UILongPressGestureRecognizer alloc] initWithTarget:self action:#selector(longPress_recognized:)];
longPressRecognizer.minimumPressDuration = 0.1f;
[viewMap addGestureRecognizer:longPressRecognizer];
}
return self;
}
- (MKOverlayRenderer*)mapView:(MKMapView*)mapView rendererForOverlay:(id<MKOverlay>)overlay
{
// reuse the renderer if already existent
if (self->renderer == nil)
{
NSLog(#" renderer is nil ==> creating");
renderer = [[MKPolygonRenderer alloc] initWithPolygon:overlay];
renderer.fillColor = [[UIColor darkGrayColor] colorWithAlphaComponent:0.4];
renderer.strokeColor = [UIColor greenColor];
renderer.lineWidth = 1;
}
else
NSLog(#" renderer is not nil ==> reusing");
return self->renderer;
}
- (void) longPress_recognized:(UILongPressGestureRecognizer*)sender
{
if (sender.state == UIGestureRecognizerStateBegan)
{
// begin drag
// check if and if yes, which polygon point is touched
// set indexOfSelectedPoint
}
else if (sender.state == UIGestureRecognizerStateChanged)
{
// drag move
if (indexOfSelectedMapPoint == -1)
return;
// get the coordinate of the user touch location
CLLocationCoordinate2D c = [self->viewMap convertPoint:[sender locationInView:self->viewMap] toCoordinateFromView:self->viewMap];
// update the coordinate of touched polygon point
self->renderer.polygon.points[indexOfSelectedMapPoint] = MKMapPointForCoordinate(c);
// this line causes the trouble
[renderer invalidatePath];
}
else if (sender.state == UIGestureRecognizerStateEnded || sender.state == UIGestureRecognizerStateCancelled)
{
// drag end
// reset states
}
}
my test project is using ARC. The profiler is not complaining about memory leaks.
is anybody having similar issues?
am i doing something completely wrong here?
is there a better way of doing this?
thanks for the help in advance