Unable to get data from a div tag using HTML parsing (hpple) in iPhone - iphone

Question

I am trying to parse the below link using hpple:
http://www.decanter.com/news/wine-news/529748/mimimum-pricing-opponents-slam-cameron-speech
Code:
- (void)parseURL:(NSURL *)url {
NSData *htmlData = [NSData dataWithContentsOfURL:url];
TFHpple *xpathParser = [[TFHpple alloc] initWithHTMLData:htmlData];
NSArray *elements = [xpathParser searchWithXPathQuery:#"<div class=\"body\" id=\"article-529748-body\">"];
NSLog(#"elements %#",elements);
TFHppleElement *element = [elements objectAtIndex:0];
NSString *myTitle = [element content];
[xpathParser release];
}
but it is crashing. Crash Report:
XPath error : Invalid expression
<div class="body" id="article-529748-body">
^
XPath error : Invalid expression
<div class="body" id="article-529748-body">
^
How to solve this issue? why my elements array is empty? Am I parsing in a wrong way? I want to get the information available in that div tag.

Answer 1

Check that your elements array is not empty
- (void)parseURL:(NSURL *)url {
NSData *htmlData = [NSData dataWithContentsOfURL:url];
TFHpple *xpathParser = [[TFHpple alloc] initWithHTMLData:htmlData];
NSArray *elements = [xpathParser searchWithXPathQuery:#"<div class=\"body\" id=\"article-529748-body\">"];
NSLog(#"elements %#",elements);
if([elements count]){
TFHppleElement *element = [elements objectAtIndex:0];
}
NSString *myTitle = [element content];
[xpathParser release];
}

Answer 2

Try changing this:
NSArray *elements = [xpathParser searchWithXPathQuery:#"<div class=\"body\" id=\"article-529748-body\">"];
To:
NSArray *elements = [xpathParser searchWithXPathQuery:#"//div [#class='body'] [#id=\'article-529748-body\']"];

Answer 3

Writing this (2 years later!) in case it's useful to someone else with a similar problem.
In order to parse the html within the div, you need to
use syntax similar (single-quotes don't need to be escaped) to that quoted by JamMySon on this page
remember that [element content] only gives you the content( if any) for that node , NOT its children.
Because of this you may need to use recursion to walk though the div's node-tree.
Code (ARC):
- (void) decanterHpple{
NSURL *url = [NSURL URLWithString:#"http://www.decanter.com/news/wine-news/529748/mimimum-pricing-opponents-slam-cameron-speech"];
NSData *htmlData = [NSData dataWithContentsOfURL:url];
TFHpple *pageParser = [TFHpple hppleWithHTMLData:htmlData];
NSString *queryString = #"//div[#id='article-529748-body']";//1.works with unescaped single-quotes(') AND 2.No need for class='' when using id=''
NSArray *elements = [pageParser searchWithXPathQuery:queryString];
//old code ~ slightly amended
if([elements count]){
TFHppleElement *element = [elements objectAtIndex:0];
NSString *myTitle = [element content];
NSLog(#"myTitle:%#",myTitle );
}
//new code
NSString *theText = [self stringFromWalkThruNodes:elements];
NSLog(#"theText:%#",theText );
}
using this recursive method:
- (NSString*) stringFromWalkThruNodes:(NSArray*) nodes {
static int level = 0;//level is only useful for keeping track of recursion when stepping through with a breakpoint
level++;//put breakpoint here...
NSString *text = #"";
for (TFHppleElement *element in nodes){
if (element.content) {
text = [text stringByAppendingString:element.content];
}
if (element.children) {
NSString *innerText = [self stringFromWalkThruNodes:element.children];
text = [text stringByAppendingString:innerText];
}
}
level--;
return text;
}
This gives the output:
2014-10-22 19:44:07.996 Decanted[10148:a0b] myTitle:(null)
2014-10-22 19:44:07.997 Decanted[10148:a0b] theText:
On a visit to a hospital in north-east England, Mr Cameron is to call for the drinks industry to do more to tackle a problem which
costs the National Health Service £2.7bn a year.A ban on the sale of
alcohol below cost price - less than the tax paid on it - is set to be
introduced in England and Wales from 6 April, but ministers are
expected to push for a higher minimum price for drink.Opponents of a
minimum unit price say it is unfair because it penalises all drinkers,
not just binge or problem drinkers.Responding to the Prime Minister’s
comments, Wine and Spirit Trade Association spokesman Gavin Partington
reiterated the drinks indusry’s commitment ‘to helping the Government
tackle alcohol misuse, alongside other stakeholders.‘This is why we
are working hard through the Public Health Responsibility Deal on a
range of initiatives to promote responsible drinking.’These
initiatives, Partington said, include the expansion of Community
Alcohol Partnerships across the UK and a national campaign by
retailers to raise consumer awareness about the units of alcohol in
alcoholic drinks.Partington said, ‘Unlike these measures, minimum unit
pricing is a blunt tool which would both fail to address the problem
of alcohol misuse and punish the vast majority of responsible
consumers. As Government ministers acknowledge, it is also probably
illegal'.Decanter is also against the scheme, calling it
‘fundamentally flawed.’‘The real problem,’ editor Guy Woodward has
said, ‘lies with supermarkets who use wine as a loss-leader, slashing
margins, bullying suppliers and dragging down prices in order to
attract customers…Selling wine at a loss helps neither consumers nor
the trade.’Other opponents of the scheme include the British Beer and
Pub Association, which told the BBC there was ‘a danger it would be
done through higher taxation, which would be hugely damaging to
pub-goers, community pubs and brewers, costing thousands of vital
jobs.’It is thought any move toward minimum pricing could also be
illegal under European competition law, which is aimed at pushing down
prices for consumers and allowing firms to operate in a free
market.
PS. Only started playing with Hpple this p.m. after reading the aforementioned Wenderlich tutorial; I'm sure someone more experienced may come up with a more elegant solution!