IPhone: memory leak on auto-implemented object?

Question

I am using the XMLParser class, which contains an array with XMLElement objects. XMLElement is highlighted using an autodetect operation. However, for some reason, I get a memory leak (using tools) on this line:

self.currentElement = [[[XMLElement alloc] init] autorelease];

I also release the XMLParser object in the caller class. I highlighted the “problematic” lines in the XMLParser source code below as a comment.

I really tried everything to fix this, but unfortunately I do not understand why this is happening at all. Any help is appreciated!

Many thanks!

// --- XMLElement

#import <Foundation/Foundation.h>


@interface XMLElement : NSObject {
     NSDictionary *attributes;
     NSMutableArray *children;
     NSString *textValue;
     NSString *tagName;
     XMLElement *parentElement;
}

-(id) init;
-(void) addChild:(XMLElement*) child;

@property(nonatomic, retain) NSDictionary *attributes;
@property(nonatomic, retain) NSMutableArray *children;
@property(nonatomic, retain) NSString *textValue;
@property(nonatomic, retain) NSString *tagName;
@property(nonatomic, retain) XMLElement *parentElement;

@end


#import "XMLElement.h"


@implementation XMLElement

@synthesize attributes, children, textValue, parentElement, tagName;

-(id)init {
     if(self = [super init]) {
          children = [[NSMutableArray alloc] init];
     }
     return self;
}

-(void) addChild:(XMLElement*) child{
     [self.children addObject:child];
}

- (void)dealloc {
     [attributes release];
     [children release];
     [textValue release];
     [tagName release];
     [parentElement release];
    [super dealloc];
}

@end





// --- XMLParser

#import <Foundation/Foundation.h>
#import "XMLElement.h"

@interface XMLParser : NSObject<NSXMLParserDelegate> {
     XMLElement *currentElement;
     XMLElement *currentParentElement;
     NSMutableString *currentElementValue;
}

- (BOOL)parseData: (NSData*) dataToParse;

- (void)parser:(NSXMLParser *)parser didStartElement:(NSString *)elementName
  namespaceURI:(NSString *)namespaceURI qualifiedName:(NSString *)qualifiedName
     attributes:(NSDictionary *)attributeDict;

- (void)parser:(NSXMLParser *)parser foundCharacters:(NSString *)string;

- (void)parser:(NSXMLParser *)parser didEndElement:(NSString *)elementName
  namespaceURI:(NSString *)namespaceURI qualifiedName:(NSString *)qName;

@property (nonatomic, retain) XMLElement *currentParentElement;
@property (nonatomic, retain) XMLElement *currentElement;
@property (nonatomic, retain) NSMutableString *currentElementValue;

@end


#import "XMLParser.h"


@implementation XMLParser

@synthesize currentElementValue, currentElement, currentParentElement;

- (BOOL)parseData: (NSData*) dataToParse {

     NSXMLParser *parser = [[NSXMLParser alloc] initWithData:dataToParse];
     [parser setDelegate:self];
     BOOL success = [parser parse];
     [parser release];
     return success;
}

- (void)parser:(NSXMLParser *)parser didStartElement:(NSString *)elementName
  namespaceURI:(NSString *)namespaceURI qualifiedName:(NSString *)qualifiedName
     attributes:(NSDictionary *)attributeDict{
     if(currentElement){
          self.currentParentElement = currentElement;
     }


     // ------------------------------------------------------------
     // Instruments is marking this line as source of the leak with 90%
     self.currentElement = [[[XMLElement alloc] init] autorelease];
     // --------

     currentElement.tagName = elementName;
     currentElement.attributes = attributeDict;
     currentElement.parentElement = self.currentParentElement;
     if(self.currentParentElement){
          [self.currentParentElement addChild:currentElement]; // and this one with 10%
     }

     self.currentElementValue = nil;
}

- (void)parser:(NSXMLParser *)parser foundCharacters:(NSString *)string{
     if(!currentElement) {
          return;
     }

     if(currentElementValue == nil)
          self.currentElementValue = [NSMutableString stringWithString:string];
     else
          [currentElementValue appendString:string];
}

- (void)parser:(NSXMLParser *)parser didEndElement:(NSString *)elementName
  namespaceURI:(NSString *)namespaceURI qualifiedName:(NSString *)qName{
     if(currentElement == nil){
          if( currentParentElement.parentElement){
               self.currentParentElement = currentParentElement.parentElement;
          }
     }else{
          currentElement.textValue = currentElementValue; 
          [currentElementValue release];
          currentElementValue = nil;
          self.currentParentElement = currentElement.parentElement;
          currentElement = nil;
     }
}

- (void)dealloc {
     [currentParentElement release];
     [currentElement release];
    [super dealloc];
}

@end

Answer 1

currentElement dealloc XMLParser.

autorelease, retain, ( ).

UPDATE: self.currentElement = nil;, , currentElement = nil;.

Answer 2

:

self.currentElement = [[[XMLElement alloc] init] autorelease];

currentElement ( retain).

, parser:didEndElement:namespaceURI:qualifiedName:, :

currentElement = nil;

, currentElement.

Answer 3

, Apple. ...

Answer 4

XMLParser ? , NSAutoReleasePool , [[[XMLElement alloc] init] autorelease] .

Answer 5

Guys. reason is just one simple thing

instead

@property(nonatomic, retain) XMLElement *parentElement;

it should be

@property(nonatomic, assign) XMLElement *parentElement;

also you need to remove [parentElement release]fromdealloc

Cause

is that you create circular links. from parent to child and chils to parent

and when you implement the parser object, the elements are still output to memory using the pointer xount> 0