A WHATWG-compliant HTML parser with CSS selectors in Objective-C and Foundation. It parses HTML just like a browser.
#import <HTMLReader/HTMLReader.h>
// Parse a string and find an element.
NSString *markup = @"<p><b>Ahoy there sailor!</b></p>";
HTMLDocument *document = [HTMLDocument documentWithString:markup];
NSLog(@"%@", [document firstNodeMatchingSelector:@"b"].textContent);
// => Ahoy there sailor!
// Wrap one element in another.
HTMLElement *b = [document firstNodeMatchingSelector:@"b"];
NSMutableOrderedSet *children = [b.parentNode mutableChildren];
HTMLElement *wrapper = [[HTMLElement alloc] initWithTagName:@"div"
attributes:@{@"class": @"special"}];
[children insertObject:wrapper atIndex:[children indexOfObject:b]];
b.parentNode = wrapper;
NSLog(@"%@", [document.rootElement serializedFragment]);
// => <html><head></head><body><p><div class="special"> \
<b>Ahoy there sailor!</b></div></p></body></html>
// Load a web page.
NSURL *URL = [NSURL URLWithString:@"https://github.com/nolanw/HTMLReader"];
NSURLSession *session = [NSURLSession sharedSession];
[[session dataTaskWithURL:URL completionHandler:
^(NSData *data, NSURLResponse *response, NSError *error) {
NSString *contentType = nil;
if ([response isKindOfClass:[NSHTTPURLResponse class]]) {
NSDictionary *headers = [(NSHTTPURLResponse *)response allHeaderFields];
contentType = headers[@"Content-Type"];
}
HTMLDocument *home = [HTMLDocument documentWithData:data
contentTypeHeader:contentType];
HTMLElement *div = [home firstNodeMatchingSelector:@".repository-description"];
NSCharacterSet *whitespace = [NSCharacterSet whitespaceAndNewlineCharacterSet];
NSLog(@"%@", [div.textContent stringByTrimmingCharactersInSet:whitespace]);
// => A WHATWG-compliant HTML parser in Objective-C.
}] resume];You have choices:
-
Copy the files in the Code folder into your project.
-
Add the following line to your Cartfile:
github "nolanw/HTMLReader" -
Add the following line to your Podfile:
pod "HTMLReader" -
Clone this repository (perhaps add it as a submodule), add
HTMLReader.xcodeprojto your project/workspace, and addlibHTMLReader.ato your iOS target orHTMLReader.frameworkto your OS X target.
HTMLReader has no dependencies other than Foundation.
I needed to scrape HTML like a browser. I couldn't find a good choice for iOS.
libxml2 ships with iOS. It parses a variant of HTML 4 and does not handle broken markup like a modern browser.
Other Objective-C libraries I came across (e.g. hpple and Ono) use libxml2 and inherit its shortcomings.
There are C libraries such as Gumbo or Hubbub, but you need to shuffle data to and from Objective-C.
WebKit ships with iOS, but its HTML parsing abilities are considered private API. I consider a round-trip through UIWebView inappropriate for parsing HTML. And I didn't make it very far into building my own copy of WebCore.
Google Toolbox for Mac will escape and unescape strings for HTML (e.g. & ⇔ &) but, again, not like a modern browser. For example, GTM will not unescape A (note the missing semicolon).
CFStringTransform does numeric entities via (the reversible) kCFStringTransformToXMLHex, but that rules out named entities.
HTMLReader continually runs html5lib's tokenization and tree construction tests, ignoring the tests for <template> (which HTMLReader does not implement).
HTMLReader is continually tested on iOS versions 7.0, 7.1, and 8.1, as well as OS X versions 10.9 and 10.10. It should work on down to iOS 5 and OS X 10.7 but no automated testing is done.
Given all that:
HTMLReader is used by at least one shipping app.
I'm not sure.
Included in the project is a utility called Benchmarker. It knows how to run three tests:
- Parsing a large HTML file. In this case, the 7MB single-page HTML specification.
- Escaping and unescaping entities in the large HTML file.
- Running a bunch of CSS selectors. Basically copied from a WebKit performance test.
Changes to HTMLReader should not cause these benchmarks to run slower. Ideally changes make them run faster!
Bugs can be reported, and features can be requested, using the issue tracker. Or get in touch directly if you'd prefer.
HTMLReader is in the public domain.
HTMLReader is developed by Nolan Waite.
Thanks to Chris Williams for contributing the implementation of CSS selectors.