iPhone : Memory Management

Question

Can someone tell me what I am doing wrong here? I use this method to draw image. But something in the code seems to not be released properly because every-time I call a this method and my application memory footprint increases.

Here,I am providing method which increase my memory.

-(void)imagemaking
{
UIGraphicsEndImageContext();
NSString *responseString = [[NSString alloc] initWithData:responseData encoding:NSUTF8StringEncoding];

SBJSON *parser = [[SBJSON alloc] init];

statuses = [parser objectWithString:responseString
                              error:nil];
[parser release];


networkConnection.image = [UIImage imageNamed:@"NetworkTrans1.png"];


[updateTimeClock setImage:[UIImage imageNamed:@"GreenClock.png"] forState:UIControlStateNormal];

NSArray *segment = [[NSArray alloc]init];
segment = [statuses valueForKey:@"Segments"];

int linewidth = 3;

CGSize polyimagesize = CGSizeMake(self.mapView.frame.size.width , self.mapView.frame.size.height);

UIGraphicsBeginImageContextWithOptions(polyimagesize, NO, 0);
CGContextRef context = UIGraphicsGetCurrentContext();
CGContextSetLineWidth(context, linewidth);

CGContextSetAlpha(context, 0.6);    

for(NSDictionary *route in segment) {

    NSString *locations = [route valueForKey:@"Locations"];

    if (locations && ([locations length]/16 > 1)) {       

        UIColor *color = [UIColor blueColor];
        CGContextSetStrokeColorWithColor(context, color.CGColor);

        for (int i = 0; i <= locations.length - 32; i += 32) {

            CLLocationCoordinate2D coordinates;
            coordinates.latitude = hexDecode_iPhone([locations substringWithRange:NSMakeRange(i, 16)]);
            coordinates.longitude = hexDecode_iPhone([locations substringWithRange:NSMakeRange(i+16, 16)]);

            CGPoint point = [mapView convertCoordinate:coordinates toPointToView:self.mapView];

            if (i == 0)
                CGContextMoveToPoint(context, point.x, point.y);
            else
                CGContextAddLineToPoint(context, point.x, point.y);
        }

        CGContextStrokePath(context);

    }        
}       

madeimage =  UIGraphicsGetImageFromCurrentImageContext();

UIGraphicsEndImageContext();
[responseString release];   
[segment release];

}

As per my Investigation,Memory foot print increase because of CoreGraphics.But i don't know how to reduce memory usage or which object is increase the memory usage.Please provide guide-line .

Thanks in advance!

Answer 1

You are assigning [statuses valueForKey:@"Segments"]; to segment and loosing address previously allocated by [[NSArray alloc]init];

NSArray *segment = [[NSArray alloc]init]; //Array #1
segment = [statuses valueForKey:@"Segments"]; //Array #2 (replaces #1)

Final release is not aware of previously allocated memory address; it can only release array #2.

[segment release];

So the statement that causes the first array to be leaked is at:

segment = [statuses valueForKey:@"Segments"];

Answer 2

take a temporary array and assign it to your segment array

NSArray *tempArray = [[NSArray alloc]init];

NSArray *segment=tempArray;

segment = [statuses valueForKey:@"Segments"];

[tempArray release];

This will remove the memory leak being caused by segmentarray.