xml解析期间出现内存泄漏问题？

Question

I got strange problem of memory leaks,

Now my code is,

-(NSMutableDictionary *)getParsedWallpaperData{
NSMutableDictionary *dataDictionary = [NSMutableDictionary dictionary];

NSData *xmlData = [NSData dataWithContentsOfFile:[[NSBundle mainBundle] pathForResource:@"Wallpaper" ofType:@"xml"]];
TBXML *tbXml = [[TBXML alloc] initWithXMLData:xmlData error:nil];

//TBXML *tbXml = [[TBXML tbxmlWithXMLData:xmlData error:nil] autorelease];

@synchronized(self){
    TBXMLElement *rootXMLElement = tbXml.rootXMLElement;

    if(rootXMLElement)
    {
        TBXMLElement *paging = [TBXML childElementNamed:kPaging parentElement:rootXMLElement];
        NSMutableDictionary *pagingData = [[NSMutableDictionary alloc] init];
        if(paging){
            TBXMLElement *totalPages = [TBXML childElementNamed:kTotalPages parentElement:paging];
            NSString *totalPagesString = [TBXML textForElement:totalPages];
            [pagingData setObject:totalPagesString forKey:@"TotalPages"];

            TBXMLElement *currentPage = [TBXML childElementNamed:kCurrentPage parentElement:paging];
            NSString *currentPageString = [TBXML textForElement:currentPage];
            [pagingData setObject:currentPageString forKey:@"CurrentPage"];

            TBXMLElement *prevPage = [TBXML childElementNamed:kPerviousPage parentElement:paging];
            NSString *prevPageString = [TBXML textForElement:prevPage];
            [pagingData setObject:prevPageString forKey:@"PreviousPage"];

            TBXMLElement *nextPage = [TBXML childElementNamed:kNextPage parentElement:paging];
            NSString *nextPageString = [TBXML textForElement:nextPage];
            [pagingData setObject:nextPageString forKey:@"NextPage"];
        }
        [dataDictionary setObject:pagingData forKey:@"PagingInfo"];
        [pagingData release];
        pagingData = nil;

        TBXMLElement *totalItems = [TBXML childElementNamed:kTotalItems parentElement:rootXMLElement];
        NSString *totalItemsString = [TBXML textForElement:totalItems];
        [dataDictionary setObject:totalItemsString forKey:@"TotalItems"];

        NSMutableArray *itemArray = [[NSMutableArray alloc] initWithCapacity:[totalItemsString intValue]]; 

        TBXMLElement *items = [TBXML childElementNamed:kItems parentElement:rootXMLElement];
        if(items){
            TBXMLElement *item = [TBXML childElementNamed:kItem parentElement:items];
            while (item) {
                NSMutableDictionary *itemInfoDict = [[NSMutableDictionary alloc] init];
                TBXMLElement *title = [TBXML childElementNamed:kTitle parentElement:item];
                NSString *titleString = [TBXML textForElement:title];
                [itemInfoDict setObject:titleString forKey:@"Title"];

                TBXMLElement *image1 = [TBXML childElementNamed:kImage1 parentElement:item];
                NSString *image1String = [TBXML textForElement:image1];
                [itemInfoDict setObject:image1String forKey:@"Image1"];

                TBXMLElement *image2 = [TBXML childElementNamed:kImage2 parentElement:item];
                NSString *image2String = [TBXML textForElement:image2];
                [itemInfoDict setObject:image2String forKey:@"Image2"];

                TBXMLElement *image3 = [TBXML childElementNamed:kImage3 parentElement:item];
                NSString *image3String = [TBXML textForElement:image3];
                [itemInfoDict setObject:image3String forKey:@"Image3"];

                TBXMLElement *thumbnail = [TBXML childElementNamed:kThumbnail parentElement:item];
                NSString *thumbnailString = [TBXML textForElement:thumbnail];
                [itemInfoDict setObject:thumbnailString forKey:@"Thumbnail"];

                [itemArray addObject:itemInfoDict];
                [itemInfoDict release];
                itemInfoDict = nil;
                item = item -> nextSibling;
            }
        }
        [dataDictionary setObject:itemArray forKey:@"ImagesInfo"];
        [itemArray release];
        itemArray = nil;
    }
}

[tbXml release];
tbXml = nil; 
return dataDictionary;
 }

I found memory leak only TBXML *tbXml = [[TBXML alloc] initWithXMLData:xmlData error:nil]; on this line, even though i manually release tbXml object,

Please suggest me y this happening?

Thanks,

Answer 1

Well, if it's the root element there that is shown as leaking, I'm wondering if one of the accessors like childElementNamed is causing it (by returning something that acts like a NSString but really also has optimized pointers stored back to the root element). Can you look at the implementation of childElementNamed ? A relatively quick way to alter your code to ensure it's not that would be to wrap any NSString result you were about to store in your dataDictionary there with a [NSString stringWithFormat:@"%@", [TBXML textForElement:fooTitle]] call.

Also, you could wrap this function in a @nsautoreleasepool macro, if TBXML is creating a lot of autoreleased objects.

As a final suggestion, you should look at ARC if you can (ie, if you are deploying to iOS 4+).

Answer 2

Add this line at the top of your function:

NSAutoreleasePool *Pool=[[NSAutoreleasePool alloc]init];

and add this line at the bottom of your function before "return" statement :

[Pool drain];

May this will help you out.