iOS NSXMLParsing未成形的HTML [英] iOS NSXMLParsing unformed HTML
问题描述
这是我的解析img src图像链接的源代码，这个链接来自RSS feed生成的不完整的html ...我知道NSXML只解析XML，但我希望它可以通过乱七八糟
我试图只检索在src属性中找到的FIRST图像链接，我在每个元素名称中找到了名为IMG的nsData它具有src属性，然后将它保存到另一个类的NSString * img中。 img标签不完全相同，例如nsData的一个实例将只包含一个图像实例，如以下任何一个：
< img class =ms-rteStyle-photoCreditsrc =www.imagelinkthatineed.com我不需要
< img alt =src =www.imagelinkineedfortableimagecellpreview我不需要
< img class =ms-rteStyle-photoCreditsrc =www.IneedThisLink.com我不需要的东西
似乎生成NSLog输出的类是第一个。
我怎样才能让解析器方法真正运行？
考虑到有一种方法，是否有推荐的更简单的方法？
#importHtmlParser.h
#importArticleItem.h
@implementation HtmlParser
@synthesize elementArray;
- （HtmlParser *）InitHtmlByString：（NSString *）string {
// NSString * description = [NSString string];
NSData * nsData = [[NSData alloc] initWithContentsOfFile：（NSString *）string];
elementArray = [[NSMutableArray alloc] init];
parser = [[NSXMLParser alloc] initWithData：nsData];
parser.delegate = self;
[解析器解析];
如果我NSLog（@％@，nsData）;在这个方法体中，输出吐出原始的HTML。
currentHTMLElement = [ArticleItem alloc];
返回自我; （NSXMLParser *）解析器didStartElement：（NSString *）elementName namespaceURI：（NSString *）namespaceURI qualifiedName：（NSString *）qualifiedName属性：（NSDictionary *）attributeDict $ b（void）解析器： $ b {
if（[elementName isEqualToString：@img src]）{
currentHTMLElement = [[ArticleItem alloc] init];
}
NSLog（@\t％@ found a％@ element，self，elementName）; （NSXMLParser *）解析器foundCharacters：（NSString *）string
{
if（！currentHTMLElement）
currentHTMLElement = [[NSMutableString alloc] initWithString：string];
NSLog（@处理值：％@，currentHTMLElement）; （NSString *）qName
{
}
- （void）解析器：（NSXMLParser *）解析器didEndElement：（NSString *）elementName namespaceURI：（NSString *）namespaceURI qualifiedName： if（[elementName isEqualToString：@img src]）
{
currentHTMLElement.img = elementName;
[elementArray addObject：currentHTMLElement];
currentHTMLElement = nil;
currentNodeContent = nil;
}
else
{
if（currentHTMLElement！= nil&& elementName！= nil&&（[elementName isEqualToString：@img src]））
{
[currentHTMLElement setValue：currentHTMLElement forKey：elementName];
}
}
currentHTMLElement = nil;
}
@end
感谢您的想法。
鉴于HTML通常不是格式良好的XML， NSXMLParser 可能无法正常工作。如果你想解析HTML，你可以参考这篇Ray Wenderlich的文章，如何在iOS上解析HTML 。如果您已按照这些说明进行操作并将Hpple添加到项目中，则可以像这样检索图像 src 属性：
#importTFHpple.h
- （void）retrieveImageSourceTagsViaHpple：（NSURL *）url
{
NSData * data = [NSData dataWithContentsOfURL：url];
TFHpple * parser = [TFHpple hppleWithHTMLData：data];
NSString * xpathQueryString = @// img;
NSArray * nodes = [parser searchWithXPathQuery：xpathQueryString];
for（TFHppleElement *节点中的元素）
{
NSString * src = [element objectForKey：@src];
NSLog（@img src：％@，src）;
$ / code $ / pre
$ hr
或者，我说这支撑自己的反 - NSRegularExpression 响应的猛烈攻击（在我的的列表，那么你可以使用一个名为的列表，您可以使用以下稍微复杂的正则表达式：
- （无效）retrieveImageSourceTagsViaRegex：（NSURL *）url
{
NSString * string = [NSString stringWithContentsOfURL：url
encoding：NSUTF8StringEncoding
error：nil];
NSError * error = NULL;
NSRegularExpression * regex = [NSRegularExpression regularExpressionWithPattern：@（< img\\\s [\\ s \\S] *？src\\\s *？= \\ S * [ '\]（*。？）[' \ ] [\\s\\S] *>有）+？
选项：NSRegularExpressionCaseInsensitive
错误：& error];
[regex enumerateMatchesInString：string
options：0
range：NSMakeRange（0，[string length]）
usingBlock：^（NSTextCheckingResult * result，NSMatchingFlags flags， BOOL * stop）{
NSString * src = [string substringWithRange：[result rangeAtIndex：2]];
NSLog（@img src：％@，src）;
}];
如果您想使用 NSXMLParser ，它看起来像这样：
- （void）retrieveImageSourceTagsViaNSXMLParser ：（NSURL *）url
{
NSXMLParser * parser = [[NSXMLParser alloc] initWithContentsOfURL：url];
parser.delegate = self;
[解析器解析]; （NSXMLParser *）解析器didStartElement：（NSString *）elementName namespaceURI：（NSString *）
$ b #pragma mark - NSXMLParserDelegate方法
$ b $ ）namespaceURI qualifiedName：（NSString *）qName attributes：（NSDictionary *）attributeDict
{
if（[elementName isEqualToString：@img]）
{
NSString * src = attributeDict [@ SRC];
NSLog（@img src：％@，src）;
根据我的经验，问题是 NSXMLParser 在解析HTML时不如LibXML2 / Hpple成功。我发现在一些简单的页面上，上述工作很好。但在其他情况下，情况并非如此。底线，虽然 NSXMLParser 在解析格式良好的XML方面很出色，但我会谨慎使用它来解析HTML。
This is my method body for parsing "img src" image links from poorly formed html generated by an RSS feed... I am aware that NSXML only parses XML, but I have this hope that it can stumble through the mess to find these miniscule image links from messy html.
I'm trying to retrieve ONLY the FIRST image link found in the src attribute I find in each element name called IMG in nsData that has a src attribute and then save it to a NSString *img in another class. The img tags are not all the same, for instance an instance of nsData will contain only one image instance like any one of these:
< img class="ms-rteStyle-photoCredit" src="www.imagelinkthatineed.com" stuff I don't need
< img alt="" src="www.imagelinkineedfortableimagecellpreview" stuff I don't need
< img class="ms-rteStyle-photoCredit" src="www.IneedThisLink.com" more stuff I don't need
The only class that seems to generate NSLog output is the first one.
How can I get the parser methods to actually run ?
Given that there's a way, is there a different, simpler way you recommend?
#import "HtmlParser.h"
#import "ArticleItem.h"
@implementation HtmlParser
@synthesize elementArray;
- (HtmlParser *) InitHtmlByString:(NSString *)string {
// NSString *description = [NSString string];
NSData *nsData = [[NSData alloc] initWithContentsOfFile:(NSString *)string];
elementArray = [[NSMutableArray alloc] init];
parser = [[NSXMLParser alloc] initWithData:nsData];
parser.delegate = self;
[parser parse];
If I NSLog(@"%@", nsData); in this method body, the output spits out the raw HTML.
currentHTMLElement = [ArticleItem alloc];
return self;
}
- (void)parser:(NSXMLParser *)parser didStartElement:(NSString *)elementName namespaceURI:(NSString *)namespaceURI qualifiedName:(NSString *)qualifiedName attributes:(NSDictionary *)attributeDict
{
if ([elementName isEqualToString:@"img src"]) {
currentHTMLElement = [[ArticleItem alloc] init];
}
NSLog(@"\t%@ found a %@ element", self, elementName);
}
- (void) parser:(NSXMLParser *)parser foundCharacters:(NSString *)string
{
if (!currentHTMLElement)
currentHTMLElement = [[NSMutableString alloc] initWithString:string];
NSLog(@"Processing Value: %@", currentHTMLElement);
}
- (void) parser:(NSXMLParser *)parser didEndElement:(NSString *)elementName namespaceURI:(NSString *)namespaceURI qualifiedName:(NSString *)qName
{
if ([elementName isEqualToString:@"img src"])
{
currentHTMLElement.img = elementName;
[elementArray addObject:currentHTMLElement];
currentHTMLElement = nil;
currentNodeContent = nil;
}
else
{
if (currentHTMLElement !=nil && elementName != nil && ([elementName isEqualToString:@"img src"]))
{
[currentHTMLElement setValue:currentHTMLElement forKey:elementName];
}
}
currentHTMLElement = nil;
}
@end
Thank you for your thoughts.
解决方案 Given that HTML is generally not well-formed XML, NSXMLParser might not work. If you want to parse HTML, you might refer to this Ray Wenderlich article, How to Parse HTML on iOS. If you've followed those instructions and have added Hpple to your project, you can then retrieve the image src attributes like so:
#import "TFHpple.h"
- (void)retrieveImageSourceTagsViaHpple:(NSURL *)url
{
NSData *data = [NSData dataWithContentsOfURL:url];
TFHpple *parser = [TFHpple hppleWithHTMLData:data];
NSString *xpathQueryString = @"//img";
NSArray *nodes = [parser searchWithXPathQuery:xpathQueryString];
for (TFHppleElement *element in nodes)
{
NSString *src = [element objectForKey:@"src"];
NSLog(@"img src: %@", src);
}
}
Alternatively, and I say this bracing myself for the onslaught of anti-NSRegularExpression responses (in the vein of my all-time favorite Stack Overflow answer), if you want a list of img tags in an html file, you can use the following somewhat complicated regular expression:
- (void)retrieveImageSourceTagsViaRegex:(NSURL *)url
{
NSString *string = [NSString stringWithContentsOfURL:url
encoding:NSUTF8StringEncoding
error:nil];
NSError *error = NULL;
NSRegularExpression *regex = [NSRegularExpression regularExpressionWithPattern:@"(<img\\s[\\s\\S]*?src\\s*?=\\s*?['\"](.*?)['\"][\\s\\S]*?>)+?"
options:NSRegularExpressionCaseInsensitive
error:&error];
[regex enumerateMatchesInString:string
options:0
range:NSMakeRange(0, [string length])
usingBlock:^(NSTextCheckingResult *result, NSMatchingFlags flags, BOOL *stop) {
NSString *src = [string substringWithRange:[result rangeAtIndex:2]];
NSLog(@"img src: %@", src);
}];
}
If you wanted to use NSXMLParser, it would look like so:
- (void)retrieveImageSourceTagsViaNSXMLParser:(NSURL *)url
{
NSXMLParser *parser = [[NSXMLParser alloc] initWithContentsOfURL:url];
parser.delegate = self;
[parser parse];
}
#pragma mark - NSXMLParserDelegate methods
- (void)parser:(NSXMLParser *)parser didStartElement:(NSString *)elementName namespaceURI:(NSString *)namespaceURI qualifiedName:(NSString *)qName attributes:(NSDictionary *)attributeDict
{
if ([elementName isEqualToString:@"img"])
{
NSString *src = attributeDict[@"src"];
NSLog(@"img src: %@", src);
}
}
The problem is, in my experience, NSXMLParser is less successful in parsing HTML than LibXML2/Hpple is. I find that on some simple pages, the above works great. But in other situations, it doesn't. Bottom line, While NSXMLParser is great at parsing well-formed XML, I'd be wary of using it for the parsing of HTML.
这篇关于iOS NSXMLParsing未成形的HTML的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！
