- (void)parser:(NSXMLParser *)parser didStartElement:(NSString *)elementName namespaceURI:(NSString *)namespaceURI qualifiedName:(NSString *)qName attributes:(NSDictionary *)attributeDict{
    currentKey = nil;
    [currentStringValue release];
    currentStringValue = nil;
    if([elementName isEqualToString:@"Value"]){
        //alloc some object to parse value into
    } else if([elementName isEqualToString:@"Signature"]){
        currentKey = @"Signature";
        return;
    }
}

- (void)parser:(NSXMLParser *)parser foundCharacters:(NSString *)string{
    if(currentKey){
        if(!currentStringValue){
            currentStringValue = [[NSMutableString alloc] initWithCapacity:200];
        }
        [currentStringValue appendString:string];
    }
}

-(void)parser:(NSXMLParser *)parser didEndElement:(NSString *)elementName namespaceURI:(NSString *)namespaceURI qualifiedName:(NSString *)qName{
    if([elementName isEqualToString:@"Signature"] && [currentStringValue intValue] == 804){
        ivar.signature = [currentStringValue intValue];
        return;
    }
}

类似的东西.注意我还没有在编译器上真正测试过这段代码，所以这里会有语法错误 &那里.

Something like this. Note I havent really tested this code on compiler so there will be syntax errors here & there.