Drawing on UIImage / Memory issue - objective-c

Question

Greetings,

I'm trying to draw a circle on a map. all the separate pieces of this project work independently but when I put them all together it breaks.

I setup my UI in my viewDidLoad, retaining most of it.

I then use touch events to call a my refresh map method:

-(void)refreshMap{

NSString *thePath = [NSString stringWithFormat:@"http://maps.google.com/staticmap?center=%f,%f&zoom=%i&size=640x640&maptype=hybrid",viewLatitude, viewLongitude, zoom];
NSURL *url = [NSURL URLWithString:thePath];
NSData *data = [NSData dataWithContentsOfURL:url];
UIImage *mapImage = [[UIImage alloc] initWithData:data];

mapImage = [self addCircle:(mapImage) influence:(70) latCon:(320) lonCon:(320)];
NSLog(@"-- mapimageview retaincount %i",[mapImage retainCount]);    

mapImageView.image = mapImage;
[mapImage release];}

Setup like this it will load the map with a circle once, but if the map is refreshed again it crashes.

If I comment out the mapImage release it works repeatedly but causes a memory leak.

The addCircle method I'm using:

-(UIImage *)addCircle:(UIImage *)img radius:(CGFloat)radius latCon:(CGFloat)lat lonCon:(CGFloat)lon{
int w = img.size.width;
int h = img.size.height; 
lon = h - lon;
CGColorSpaceRef colorSpace = CGColorSpaceCreateDeviceRGB();
CGContextRef context = CGBitmapContextCreate(NULL, w, h, 8, 4 * w, colorSpace, kCGImageAlphaPremultipliedFirst);

//draw the circle
CGContextDrawImage(context, CGRectMake(0, 0, w, h), img.CGImage);
CGRect leftOval = {lat- radius/2, lon - radius/2, radius, radius};
CGContextSetRGBFillColor(context, 0.0, 0.0, 1.0, 0.3);
CGContextAddEllipseInRect(context, leftOval);
CGContextFillPath(context);

CGImageRef imageMasked = CGBitmapContextCreateImage(context);
CGContextRelease(context);
CGColorSpaceRelease(colorSpace);

return [UIImage imageWithCGImage:imageMasked];}

Any insight/advise is greatly appreciated!

Answer 1

UIImage *mapImage = [[UIImage alloc] initWithData:data];
mapImage = [self addCircle:(mapImage) influence:(70) latCon:(320) lonCon:(320)];

That's not good. You're losing the reference to the contents of mapImage when you reassign it on the second line. The easiest way to fix this if probably to just add an additional variable, so you can keep track of both images.