Objective-C stringByReplacingOccurrencesOfString with regex expression

Question

I'm trying to split my string containing html code with a regex expression:

NSString* regex = @"<.*?>";
NSString* html = @"<span class="test">Test1</span><span class="test">Test2</span><span class="test">Test3</span><span class="test">Test4</span>";

html = [html stringByReplacingOccurrencesOfString:regex withString:@""];

I want to delete the span-tags.

Any ideas?

Uh-oh, regex parsing of HTML again... please see [here](http://stackoverflow.com/questions/1732348/regex-match-open-tags-except-xhtml-self-contained-tags/1732454#1732454) — dreamlax, Jan 09 '12 at 21:55
What happens when you use the code above? What's the output? What's the desired output? — PengOne, Jan 09 '12 at 21:55
@PengOne: The `stringByReplacingOccurencesOfString:withString:` method only replaces literal instances of the string, i.e. each time it encounters `"<.*?>"` it will replace it with `@""`, but since `"<.*?>"` doesn't appear in the `html` string, `html` will remain the same. — dreamlax, Jan 09 '12 at 22:01
@dreamlax: I don't think this counts as "parsing", since NthDegree isn't trying to extract semantic information. Barring malformed HTML (`<` or `>` inside another tag), it should be possible to construct a regex that just removes tags themselves. — jscs, Jan 09 '12 at 22:07
@JoshCaswell: yeah this isn't as bad, but as long as OP knows that if it were to get trickier then they need to consider a different way of parsing. — dreamlax, Jan 09 '12 at 22:10
@dreamlax the question was somewhat rhetorical with the goal of having the OP improve the quality of his question. — PengOne, Jan 09 '12 at 23:46
Bottom line: doing text munging of HTML using anything that assumes tag syntax or structure is either a one-off hack or doomed to failure. — bbum, Jan 10 '12 at 03:00

dreamlax · Answer 1 · 2013-12-05T04:03:34.113

You could probably do something like this with this method:

NSRegularExpression *re = [NSRegularExpression regularExpressionWithPattern:@"<.*?>"
                                                                    options:0
                                                                      error:NULL];

NSString *result = [re stringByReplacingMatchesInString:html
                                                options:0
                                                  range:NSMakeRange(0, [html length])
                                           withTemplate:@""];

Check what options you may need in the documentation in the link above.

score 1 · Answer 2 · edited Jul 09 '12 at 13:00

This just removes < and > characters and everything between them, which I suppose is sufficient:

 (NSString *) stripTags:(NSString *)str
{
    NSMutableString *ms = [NSMutableString stringWithCapacity:[str length]];

    NSScanner *scanner = [NSScanner scannerWithString:str];
    [scanner setCharactersToBeSkipped:nil];
    NSString *s = nil;
    while (![scanner isAtEnd])
    {
        [scanner scanUpToString:@"<" intoString:&s];
        if (s != nil)
            [ms appendString:s];
        [scanner scanUpToString:@">" intoString:NULL];
        if (![scanner isAtEnd])
            [scanner setScanLocation:[scanner scanLocation]+1];
        s = nil;
    }

    return ms;
}

score 1 · Answer 3 · answered Jan 10 '12 at 02:58

1

If your input is HTML, the use an HTML PARSER.

"parsing" HTML with a regular expression is an exercise in futility. Note that there are plenty of questions on SO that describe HTML parsing on iO/OSX.

answered Jan 10 '12 at 02:58

bbum

162,346
23
271
359

Objective-C stringByReplacingOccurrencesOfString with regex expression

3 Answers3