I m at my first experiences with iPhone development. I wrote some basic code to test the NSScanner class, and now I was looking into the Leaks tool. It seems that this code is leaking, when in the detailed stack I double-click my last call (before Apple s stuff), the incriminated line is the commented.

Can anyone help me to understand why this is leaking? from a logical point of view the result is what I expect, and I do not formally alloc anything myself (except for the xmlblock variable, which is btw autoreleased), so I would not expect the need to release anything... where I m wrong? :-)

+(NSSet *)extractXMLSectionsWithTag:(NSString *)tag fromString:(NSString *)source firstOnly:(BOOL)firstOnly
{
 if (!source)
    return nil;
 NSScanner *scanner = [NSScanner scannerWithString:source];
 NSString *openingToken = [NSString stringWithFormat:@"<%@", tag];
 NSString *closingToken = [NSString stringWithFormat:@"</%@>", tag];
 NSMutableSet *sections = [NSMutableSet set];
 NSCharacterSet *majorChar = [NSCharacterSet characterSetWithCharactersInString:@">"];

 while (![scanner isAtEnd]) {
    NSString *xmlBlock = [[[NSString alloc] init] autorelease];
    [scanner scanUpToString:openingToken intoString:NULL];
    [scanner scanString:openingToken intoString:NULL];
    [scanner scanUpToCharactersFromSet:majorChar intoString:NULL];
    [scanner scanCharactersFromSet:majorChar intoString:NULL];
    [scanner scanUpToString:closingToken intoString:&xmlBlock];
    if (![xmlBlock isEqualToString:@""]) { // Leaking line
        [sections addObject:xmlBlock];
        if (firstOnly) {
            break;
        }
    }
 }
 return [sections copy];
}