HTML解析：如何从远程站点获取链接标记 [英] HTML parsing: how to get link tag from remote site

问题描述

我有一个网站（例如 apple.com ），其中包含链接标记，例如

 < link rel =alternatetype =application / rss + xmltitle =RSShref =http：// images.apple.com/main/rss/hotnews/hotnews.rss/> 
  

那么我怎么能从它得到标题RSS和href？

更新1：
我试图使用

 NSURL请求requestWithURL：[NSURL URLWithString：@http://apple.com/]] returnsResponse：NULL error：NULL]; 
 NSString * HTMLWithFeeds = [[NSString alloc] initWithData：data encoding：NSUTF8StringEncoding]; 
  

但我现在不知道该怎么做......

更新2：

从我的帖子不清楚，但除此之外，应该在本网站找到类型链接=application / rss + xml

解决方案

您可以尝试使用正则表达式

  NSError * error = NULL; 
 NSRegularExpression * regex = [NSRegularExpression regularExpressionWithPattern：@< link。*？href =（。*？）。*？> 
选项：NSRegularExpressionCaseInsensitive 
错误：& error]; 
 
 NSArray * matches = [regex matchesInString：string 
 options：0 
 range：NSMakeRange（0，[string length]）];; 
 for（NSTextCheckingResult * match in match）{
 NSRange matchRange = [match range]; 
 NSRange firstHalfRange = [match rangeAtIndex：1]; 
 NSRange secondHalfRange = [match rangeAtIndex：2]; 
} 
  

苹果文档提供了一些关于如何进一步使用和访问匹配的例子：

https://developer.apple.com/library/ios/#documentation/Foundation/Reference/NSRegularExpression_Class/Reference/Reference.html

如像下面的正则表达式应该为hrefs做：

 < link。*？href =（。*？） *>？; 
  

I have a site (for example apple.com) which contain link tag, for example

<link rel="alternate" type="application/rss+xml" title="RSS" href="http://images.apple.com/main/rss/hotnews/hotnews.rss" />

So how I can get title "RSS" and href from it?

Update 1: I've tried to convert site into string using

NSData *data = [NSURLConnection sendSynchronousRequest:[NSURLRequest requestWithURL:[NSURL URLWithString:@"http://apple.com/"]] returningResponse:NULL error:NULL];
NSString *HTMLWithFeeds = [[NSString alloc] initWithData:data encoding:NSUTF8StringEncoding];

But I dont know what to do now...

Update 2:

It is not clear from my post, but in addition in should find at this site link with type="application/rss+xml"

解决方案

you might try using regular expressions

NSError *error = NULL;
NSRegularExpression *regex = [NSRegularExpression regularExpressionWithPattern:@"<link.*?href="(.*?)".*?>"
                                                                           options:NSRegularExpressionCaseInsensitive
                                                                             error:&error];

NSArray *matches = [regex matchesInString:string
                                  options:0
                                    range:NSMakeRange(0, [string length])];
for (NSTextCheckingResult *match in matches) {
     NSRange matchRange = [match range];
     NSRange firstHalfRange = [match rangeAtIndex:1];
     NSRange secondHalfRange = [match rangeAtIndex:2];
}

Apples documentation has some examples about how to further use and access the matches:

https://developer.apple.com/library/ios/#documentation/Foundation/Reference/NSRegularExpression_Class/Reference/Reference.html

e.g. something like the following regex should do for the hrefs:

<link.*?href="(.*?)".*?>

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