Remove HTML Tags from an NSString on the iPhone

Question

There are a couple of different ways to remove HTML tags from an NSString in Cocoa.

One way is to render the string into an NSAttributedString and then grab the rendered text.

Another way is to use NSXMLDocument's -objectByApplyingXSLTString method to apply an XSLT transform that does it.

Unfortunately, the iPhone doesn't support NSAttributedString or NSXMLDocument. There are too many edge cases and malformed HTML documents for me to feel comfortable using regex or NSScanner. Does anyone have a solution to this?

One suggestion has been to simply look for opening and closing tag characters, this method won't work except for very trivial cases.

For example these cases (from the Perl Cookbook chapter on the same subject) would break this method:

<IMG SRC = "foo.gif" ALT = "A > B">

<!-- <A comment> -->

<script>if (a<b && a>c)</script>

<![INCLUDE CDATA [ >>>>>>>>>>>> ]]>

Answer 1

A quick and "dirty" (removes everything between < and >) solution, works with iOS >= 3.2:

-(NSString *) stringByStrippingHTML {
  NSRange r;
  NSString *s = [[self copy] autorelease];
  while ((r = [s rangeOfString:@"<[^>]+>" options:NSRegularExpressionSearch]).location != NSNotFound)
    s = [s stringByReplacingCharactersInRange:r withString:@""];
  return s;
}

I have this declared as a category os NSString.