Question

I Have Rendered nearly 1000 Polygons in the map. I get the path of the polygon using

-   (CGPathRef)polyPath:(MKPolygon *)polygon
{
     MKMapPoint *points = [polygon points];
     NSUInteger pointCount = [polygon pointCount];
     NSUInteger i;
     if (pointCount < 3)
         return NULL;
     CGMutablePathRef path = CGPathCreateMutable();
     if([polygon isKindOfClass:[MKPolygon class]])
     {
            for (MKPolygon *interiorPolygon in polygon.interiorPolygons)
      {
       CGPathRef interiorPath = [self polyPath:interiorPolygon];
       CGPathAddPath(path, NULL, interiorPath);
       CGPathRelease(interiorPath);
       }
  }
     CGPoint relativePoint = [self pointForMapPoint:points[0]];
     CGPathMoveToPoint(path, NULL, relativePoint.x, relativePoint.y);
     for (i = 1; i < pointCount; i++) 
     {
            relativePoint = [self pointForMapPoint:points[i]];
            CGPathAddLineToPoint(path, NULL, relativePoint.x, relativePoint.y);
     }
     return path;
}

- (void)drawMapRect:(MKMapRect)mapRect
      zoomScale:(MKZoomScale)zoomScale
      inContext:(CGContextRef)context
{
    MultiPolygon *multiPolygon = (MultiPolygon *)self.overlay;
for (MKPolygon *polygon in multiPolygon.polygons) 
{
    if([polygon isKindOfClass:[MKPolygon class]])
    {
            CGPathRef path = [self polyPath:polygon];
            if (path) 
            {
                [self applyFillPropertiesToContext:context atZoomScale:zoomScale];
                CGContextBeginPath(context);
                CGContextAddPath(context, path);
                CGContextDrawPath(context, kCGPathEOFill);
                [self applyStrokePropertiesToContext:context atZoomScale:zoomScale];
                CGContextBeginPath(context);
                CGContextAddPath(context, path);
                CGContextSetAlpha(context,1.0);
                CGContextStrokePath(context);
            }
            CGPathRelease(path);
    }
}
}

I get leak in

CGPathRelease(interiorPath);

and

return path;

I know that i have to release path using CGPathRelease but where to release it while i have to return.

Both leaks a huge memory.
I have been working on this for days, Please help.

Thanks in Advance

Answer 1

You should rename your method to be -createPolyPath: to make it clear that it is returning a Core Foundation object that needs to be released, then in the code in which you call -createPolyPath:, you need to release it like so:

CGPathRef path = [someObjectOrClass createPolyPath:somePolygon];
// Do some stuff with the path
CGPathRelease(path);

See the “Memory Management Programming Guide for Core Foundation”: