Memory leaks while using NSXMLParser - objective-c

Question

I am having some difficulty dealing with memory leaks in the following code.
Using the leaks instrument within XCode, which shows up the memory leaks within some of my code that is used for rss parsing.
I am using XCode 4, and releasing the allocations at the foot of the code. I have tried adding releases to each local section which causes crashes or the program to stop working.
Any help of advice much appreciated!!
The code which causes the leaks:
- (void)parser:(NSXMLParser *)parser parseErrorOccurred:(NSError *)parseError {
NSString * errorString = [NSString stringWithFormat:#"Unable to download story feed from web site (Error code %i )", [parseError code]];
UIAlertView * errorAlert = [[UIAlertView alloc] initWithTitle:#"Error loading content" message:errorString delegate:self cancelButtonTitle:#"OK" otherButtonTitles:nil];
[errorAlert show];
}
- (void)parser:(NSXMLParser *)parser didStartElement:(NSString *)elementName namespaceURI:(NSString *)namespaceURI qualifiedName:(NSString *)qName attributes:(NSDictionary *)attributeDict {
currentElement = [elementName copy];
if ([elementName isEqualToString:#"item"]) {
item = [[NSMutableDictionary alloc] init];
currentImage = [[NSMutableString alloc] init];
currentTitle = [[NSMutableString alloc] init];
currentDate = [[NSMutableString alloc] init];
currentSummary = [[NSMutableString alloc] init];
currentLink = [[NSMutableString alloc] init];
}
}
- (void)parser:(NSXMLParser *)parser didEndElement:(NSString *)elementName namespaceURI:(NSString *)namespaceURI qualifiedName:(NSString *)qName {
if ([elementName isEqualToString:#"item"]) {
[item setObject:currentImage forKey:#"media"];
[item setObject:currentTitle forKey:#"title"];
[item setObject:currentLink forKey:#"link"];
[item setObject:currentSummary forKey:#"summary"];
[item setObject:currentDate forKey:#"date"];
[stories addObject:[item copy]];
}
}
- (void)parser:(NSXMLParser *)parser foundCharacters:(NSString *)string {
if ([currentElement isEqualToString:#"media"]) {
[currentImage appendString:string];
} else if ([currentElement isEqualToString:#"title"]) {
[currentTitle appendString:string];
} else if ([currentElement isEqualToString:#"link"]) {
[currentLink appendString:string];
} else if ([currentElement isEqualToString:#"description"]) {
[currentSummary appendString:string];
} else if ([currentElement isEqualToString:#"pubDate"]) {
[currentDate appendString:string];
}
}
And the releasing later on:
- (void)dealloc {
[currentElement release];
[rssParser release];
[stories release];
[item release];
[currentImage release];
[currentTitle release];
[currentDate release];
[currentSummary release];
[currentLink release];
[super dealloc];
}

Answer 1

Change the following:
UIAlertView * errorAlert = [[[UIAlertView alloc] initWithTitle:#"Error loading content" message:errorString delegate:self cancelButtonTitle:#"OK" otherButtonTitles:nil] autorelease];
This code should be executed only once:
item = [[NSMutableDictionary alloc] init];
currentImage = [[NSMutableString alloc] init];
currentTitle = [[NSMutableString alloc] init];
currentDate = [[NSMutableString alloc] init];
currentSummary = [[NSMutableString alloc] init];
currentLink = [[NSMutableString alloc] init];

Answer 2

At the start of each didStartElement: method new instances are boing created yet only releases once when the class is dealloc'ed. Thus, as suing that didStartElement: is called more than once there is a build-up of instances of the string objects.
Probably what you want is to create these instances once at the instantiation of the class and then append to them as elements are encountered.
In any event release for each allocation.