NSXMLParser不会忽略CDATA
NSXMLParser不会忽略CDATA
提问于 2013-03-22 17:24:10
我在ios开发和im尝试解析RSS文件(Xml)方面非常新。
这里是xml: (对语言很抱歉)
<item>
<category> General < / category >
<title> killed in a tractor accident , was critically injured windsurfer </ title>
<description>
< ! [ CDATA [
<div> <a href='http://www.ynet.co.il/articles/0,7340,L-4360016,00.html'> <img src = 'http://www.ynet.co. il/PicServer3/2012/11/28/4302844/YOO_8879_a.jpg ' alt =' photo: Yaron Brener 'title =' Amona 'border = '0' width = '116 'height = '116'> </ a> < / div >
] ] >
Tractor driver in his 50s near Kfar Yuval flipped and trapped underneath . Room was critically injured windsurfer hurled rocks because of strong winds and wind surfer after was moderately injured in Netanya
< / description >
<link>
http://www.ynet.co.il/articles/0 , 7340, L- 4360016 , 00.html
< / link >
<pubDate> Fri, 22 Mar 2013 17:10:15 +0200 </ pubDate>
<guid>
http://www.ynet.co.il/articles/0 , 7340, L- 4360016 , 00.html
< / guid >
<tags> Kill , car accidents , surfing < / tags >
< / item >，这里是我的and解析器代码：
- (void)parserDidStartDocument:(NSXMLParser *)parser
{
self.titles = [[NSMutableArray alloc]init];
self.descriptions = [[NSMutableArray alloc]init];
self.links = [[NSMutableArray alloc]init];
}
- (void)parser:(NSXMLParser *)parser didStartElement:(NSString *)elementName namespaceURI:(NSString *)namespaceURI qualifiedName:(NSString *)qName attributes:(NSDictionary *)attributeDict
{
if ([elementName isEqualToString:@"item"]) {
isItem = YES;
}
if ([elementName isEqualToString:@"title"]) {
isTitle=YES;
self.titlesString = [[NSMutableString alloc]init];
}
if ([elementName isEqualToString:@"description"]) {
isDesription = YES;
self.descriptionString = [NSMutableString string];
self.data = [NSMutableData data];
}
}
- (void)parser:(NSXMLParser *)parser foundCharacters:(NSString *)string{
if(isItem && isTitle){
[self.titlesString appendString:string];
}
if (isItem && isDesription) {
if (self.descriptionString)
[self.descriptionString appendString:string];
}
}
- (void)parser:(NSXMLParser *)parser foundCDATA:(NSData *)CDATABlock
{
if (self.data)
[self.data appendData:CDATABlock];
}
- (void)parser:(NSXMLParser *)parser didEndElement:(NSString *)elementName namespaceURI:(NSString *)namespaceURI qualifiedName:(NSString *)qName
{
if ([elementName isEqualToString:@"item"]) {
isItem = NO;
[self.titles addObject:self.titlesString];
[self.descriptions addObject:self.descriptionString];
}
if ([elementName isEqualToString:@"title"]) {
isTitle=NO;
}
if ([elementName isEqualToString:@"description"]) {
NSString *result = [self.descriptionString stringByTrimmingCharactersInSet:[NSCharacterSet whitespaceAndNewlineCharacterSet]];
NSLog(@"string=%@", result);
if ([self.data length] > 0)
{
NSString *htmlSnippet = [[NSString alloc] initWithData:self.data encoding:NSUTF8StringEncoding];
NSString *imageSrc = [self firstImgUrlString:htmlSnippet];
NSLog(@"img src=%@", imageSrc);
[self.links addObject:imageSrc];
}
self.descriptionString = nil;
self.data = nil;
}
}
- (NSString *)firstImgUrlString:(NSString *)string
{
NSError *error = NULL;
NSRegularExpression *regex = [NSRegularExpression regularExpressionWithPattern:@"(<img\\s[\\s\\S]*?src\\s*?=\\s*?['\"](.*?)['\"][\\s\\S]*?>)+?"
options:NSRegularExpressionCaseInsensitive
error:&error];
NSTextCheckingResult *result = [regex firstMatchInString:string
options:0
range:NSMakeRange(0, [string length])];
if (result)
return [string substringWithRange:[result rangeAtIndex:2]];
return nil;
}
@end就像我说过我对iPhone开发非常陌生一样，我花了几个小时寻找解决这个问题的方法，但什么也没找到。我决定打开一个话题，然后问几个问题：
One.解析器不会忽略CDATA所做的事情--解析一切。为什么会发生这种情况？正如您所看到的，描述本身并不在cdata中，我只有第一步，但是即使我没有使用foundCDATA：(NSData *) CDATABlock，我也得到了其余的部分。
2.我想拿图像链接，怎么做？我在网上搜索，发现很多指南只解释了使用函数foundCDATA：(NSData *) CDATABlock，但是它是如何使用的呢？我在代码中使用的方式？
请给我一个解释，这样我才能理解，，谢谢！
Stack Overflow用户
回答已采纳
发布于 2013-03-22 18:18:41
在回答你的两个问题时：
- 如果您已经实现了
foundCDATA，解析器将在该方法中解析descriptionCDATA，而不是在foundCharacters中解析。另一方面，如果您没有实现foundCDATA，则CDATA将被foundCharacters解析。因此，如果不希望foundCharacters解析CDATA，则必须实现foundCDATA。 - 如果您想要提取HTML，您必须以某种方式解析
img。您可以使用Hpple，但我可能只是倾向于使用正则表达式：
- (NSString *)firstImgUrlString:(NSString *)字符串{ NSError *NSString= NULL；NSRegularExpression *regex = [NSRegularExpression NSError]选项:NSRegularExpressionCaseIn敏感错误：&error]；NSTextCheckingResult *result = [regex : string选项:0范围:NSMakeRange(0，字符串长度)]；如果(结果)返回[string substringWithRange:result rangeAtIndex:2]；返回nil；} 还请参阅this other Stack Overflow answer，其中我演示了Hpple和regex解决方案：
例如，下面是解析描述的NSXMLParserDelegate方法，将文本(不包括CDATA)放在一个字段中，并将CDATA中的图像URL放在另一个变量中。您将不得不修改以适应您的过程，但希望这给您提供了基本的想法：
- (void)parser:(NSXMLParser *)parser didStartElement:(NSString *)elementName namespaceURI:(NSString *)namespaceURI qualifiedName:(NSString *)qName attributes:(NSDictionary *)attributeDict
{
if ([elementName isEqualToString:@"description"])
{
self.string = [NSMutableString string];
self.data = [NSMutableData data];
}
}
- (void)parser:(NSXMLParser *)parser parseErrorOccurred:(NSError *)parseError
{
NSLog(@"%s, parseError=%@", __FUNCTION__, parseError);
}
// In my standard NSXMLParser routine, I leave self.string `nil` when not parsing
// a particular element, and initialize it if I am parsing. I do it this way
// so only my `didStartElement` and `didEndElement` need to worry about the particulars
// and my `foundCharacters` and `foundCDATA` are simplified. But do it however you
// want.
- (void)parser:(NSXMLParser *)parser foundCharacters:(NSString *)string
{
if (self.string)
[self.string appendString:string];
}
- (void)parser:(NSXMLParser *)parser foundCDATA:(NSData *)CDATABlock
{
if (self.data)
[self.data appendData:CDATABlock];
}
- (void)parser:(NSXMLParser *)parser didEndElement:(NSString *)elementName namespaceURI:(NSString *)namespaceURI qualifiedName:(NSString *)qName
{
if ([elementName isEqualToString:@"description"])
{
// get the text (non-CDATA) portion
// you might want to get rid of the leading and trailing whitespace
NSString *result = [self.string stringByTrimmingCharactersInSet:[NSCharacterSet whitespaceAndNewlineCharacterSet]];
NSLog(@"string=%@", result);
// get the img out of the CDATA
if ([self.data length] > 0)
{
NSString *htmlSnippet = [[NSString alloc] initWithData:self.data encoding:NSUTF8StringEncoding];
NSString *imageSrc = [self firstImgUrlString:htmlSnippet];
NSLog(@"img src=%@", imageSrc);
}
// once I've saved the data where I want to save it, I `nil` out my
// `string` and `data` properties:
self.string = nil;
self.data = nil;
}
}页面原文内容由Stack Overflow提供。腾讯云小微IT领域专用引擎提供翻译支持
原文链接：
https://stackoverflow.com/questions/15576398
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