NSMutableString内存泄漏

Question

I am getting memory leak in instruments in the code

-(void)connectionDidFinishLoading:(NSURLConnection *)connection
{
       NSAutoreleasePool *pool = [[NSAutoreleasePool alloc] init];

     NSMutableString * res = [[[NSMutableString alloc] initWithBytes: [webData mutableBytes] length:[webData length] encoding:NSUTF8StringEncoding]autorelease];
     [webData release];
    [connection release];
        [res replaceOccurrencesOfString:@"&" withString:@"&" options:NSCaseInsensitiveSearch range:(NSRange){0,[res length]}];
    [delegate getcat:res];

    [pool drain];
}



- (void)getcat:(NSString*)xml
{

if (xmlParser) {

    [xmlParser release];
}
Cid = [[NSMutableArray alloc] init];
Categories = [[NSMutableArray alloc] init];

NSData *data = [xml dataUsingEncoding:NSUTF8StringEncoding];
xmlParser = [[NSXMLParser alloc] initWithData:data];

[xmlParser setDelegate:self];

[xmlParser setShouldResolveExternalEntities:YES];
[xmlParser parse];
[xmlParser release];

}

Is this the correct way to manage memory?

Answer 1

Instead of setting up an autorelease pool, which will actually release the string, why don't you just release it yourself? If the delegate retains the string in getcat: , you can simply release it:

- (void) connectionDidFinishLoading: (NSURLConnection *) connection
{
    // Omit the autorelease pool.

    NSMutableString * res = [[NSMutableString alloc] initWithBytes: [webData mutableBytes] length:[webData length] encoding:NSUTF8StringEncoding];
    [webData release];
    [connection release];
    [res replaceOccurrencesOfString:@"&" withString:@"&" options:NSCaseInsensitiveSearch range:NSMakeRange(0, res.length)];
    [delegate getcat:res];
    [res release];
}

---

Taking a look at getcat: , I see a problem:

[xmlParser parse];
[xmlParser release];

Usually, objects need a delegate to return results from a thread. I assume that [xmlParser parse] starts a thread. You should probably not release it before it is finished, ie you do that in parserDidEndDocument: .

This does however not explain the many leaked strings.

Answer 2

I fixed this issue

The leak is in

• (void)parser:(NSXMLParser *)parser didStartElement:(NSString *)elementName namespaceURI:(NSString *)namespaceURI qualifiedName:(NSString *)qName attributes:(NSDictionary *)attributeDict{

  currentElement = [elementName copy]; --->Always leaking in this line But leak instrument show that line

}

replace the code with self.currentElemnt=elementName