Issues with leaking XMLParser

Question

I've been trying for some time now to get xml parser working leak free and efficient but so far unsuccessful. I've removed additional fields as they are all the same.

- (void)parser:(NSXMLParser *)parser didStartElement:(NSString *)elementName namespaceURI:(NSString *)namespaceURI qualifiedName:(NSString *)qName attributes:(NSDictionary *)attributeDict{
    currentElement = [[elementName copy] autorelease];
    if ([elementName isEqualToString:@"source"]) {
        if (!currentID) {
            overlays = [[NSMutableArray alloc] init];
            currentID = [[NSMutableString alloc] init];
        } else {
            [currentID release];
            currentID = nil;
            currentID = [[NSMutableString alloc] init];
        }
    }
}

- (void)parser:(NSXMLParser *)parser didEndElement:(NSString *)elementName namespaceURI:(NSString *)namespaceURI qualifiedName:(NSString *)qName{
    if ([elementName isEqualToString:@"source"]) {
         overlay = [[NSMutableDictionary alloc] init];
         [overlay setObject:currentID forKey:@"id"];
        [overlays insertObject:overlay atIndex:[overlays count]];
        [overlay release];
        overlay = nil;
    }
}

- (void)parser:(NSXMLParser *)parser foundCharacters:(NSString *)string{
   string = [string stringByReplacingOccurrencesOfString:@"\n" withString:@""];
   string = [string stringByReplacingOccurrencesOfString:@"\t" withString:@""];
   if ([currentElement isEqualToString:@"id"]) {
        [self.currentID appendString:string];
   }
}

- (void)parserDidEndDocument:(NSXMLParser *)parser {
    [currentID release];
    currentID = nil;
    //[self addResources];
 }

Any help would be appreciated.

Answer 1

If you have declared properties for your ivars I would recommend to use them. This makes memory management easier. This is how I would write your code:

- (void)parser:(NSXMLParser *)parser didStartElement:(NSString *)elementName namespaceURI:(NSString *)namespaceURI qualifiedName:(NSString *)qName attributes:(NSDictionary *)attributeDict{
    self.currentElement = elementName;
    if ([elementName isEqualToString:@"source"]) {
        if (!self.currentID) {
            self.overlays = [NSMutableArray array];
            self.currentID = [NSMutableString string];
        } else {
            self.currentID = [NSMutableString string];
        }
    }
}

- (void)parser:(NSXMLParser *)parser didEndElement:(NSString *)elementName namespaceURI:(NSString *)namespaceURI qualifiedName:(NSString *)qName{
    if ([elementName isEqualToString:@"source"]) {
        [self.overlays addObject:
        [NSDictionary dictionaryWithObjectsAndKeys:self.currentID,@"id",nil]];
    }
}

- (void)parser:(NSXMLParser *)parser foundCharacters:(NSString *)string{
   string = [string stringByReplacingOccurrencesOfString:@"\n" withString:@""];
   string = [string stringByReplacingOccurrencesOfString:@"\t" withString:@""];
   if ([self.currentElement isEqualToString:@"id"]) {
        [self.currentID appendString:string];
   }
}

- (void)parserDidEndDocument:(NSXMLParser *)parser {
    self.currentID = nil;
}

You might also want to try Build&Analyse for your code. this may point out where you are leaking.