NSXMLParser与\n的奇怪行为

Question

我正在开发一个解析XML文件的iOS 4应用程序.一段XML是:

<?xml version="1.0" encoding="utf-8" ?>
<cards>
  <card id ="0">
    <name lang="es">The Mad</name>
    <description lang="es">...</description>
  </card>
...
</cards>

我使用以下方法进行解析<name lang="es">The Mad</name>.

#pragma mark -
#pragma mark NSXMLParserDelegate methods

- (void)parser:(NSXMLParser *)parser
didStartElement:(NSString *)elementName 
  namespaceURI:(NSString *)namespaceURI
 qualifiedName:(NSString *)qName 
    attributes:(NSDictionary *)attributeDict
{
    NSLog(@"DidStartElement: %@", elementName);
    if ([elementName isEqualToString:@"card"])
    {
        currentCard = [[Card alloc] init];
        NSString* arcaneNumber = [attributeDict objectForKey:@"id"];
        currentCard.Number = arcaneNumber;

        return;
    }
    if ([elementName isEqualToString:@"name"])
    {
        if ([[attributeDict objectForKey:@"lang"] isEqualToString:userLanguage])
        {
            currentProperty = kNameProperty;
            return;
        }
    }
    if ([elementName isEqualToString:@"description"])
    {
        if ([[attributeDict objectForKey:@"lang"] isEqualToString:userLanguage])
        {
            currentProperty = kDescriptionProperty;
            return;
        }
    }
}

- (void)parser:(NSXMLParser *)parser foundCharacters:(NSString *)string
{
    if (!currentStringValue)
    {
        // currentStringValue is an NSMutableString instance variable
        currentStringValue = [[NSMutableString alloc] initWithCapacity:50];
    }
    [currentStringValue appendString:string];
}

- (void) parser:(NSXMLParser *)parser
  didEndElement:(NSString *)elementName
   namespaceURI:(NSString *)namespaceURI
  qualifiedName:(NSString *)qName
{
    NSLog(@"DidEndElement: %@", elementName);
    if ([elementName isEqualToString:@"card"])
    {
        [cards setObject:currentCard forKey:currentCard.Number];
        [currentCard release];
        currentCard = nil;

        return;
    }

    if (currentProperty == kNameProperty)
    {
        currentProperty = kNoneProperty;
        currentCard.Name = [currentStringValue stringByTrimmingCharactersInSet:[NSCharacterSet whitespaceAndNewlineCharacterSet]];
        [currentStringValue release];
        currentStringValue = nil;

        return;
    }

    if (currentProperty == kDescriptionProperty)
    {
        currentProperty = kNoneProperty;
        currentCard.Description = currentStringValue;
        [currentStringValue release];
        currentStringValue = nil;

        return;
    }
}

之后,解析,我得到currentStringValue以下内容:

\n\nThe Mad

怎么能避免这两个'\n'？为什么我得到这两个'\n'？

这个xml文件来自Windows系统,我使用TextWrangler将其转换为Classic Mac格式.

Answer 1

该foundCharacters委托方法也得到呼吁元素之间的空白.如果在<cards>和之间有换行符,它将被调用<card id=....

我建议currentStringValue在顶部清除didStartElement以丢弃在当前元素开始之前找到的任何字符,并确保仅捕获当前元素(不在其中)内的字符foundCharacters.

在顶部didStartElement,添加:

[currentStringValue release];
currentStringValue = nil;

元素的值可能包含空格(因此删除它们didEndElement可能会导致保存与xml内容不匹配的值).