NSRegularExpression to extract text between two XML tags

Question

How to extract the value "6" between the "badgeCount" tags using NSRegularExpression. Following is the response from the server:

<?xml version="1.0" encoding="UTF-8" standalone="yes"?><badgeCount>6</badgeCount><rank>2</rank><screenName>myName</screenName>

Following is the code I tried but not getting success. Actually it goes in else part and prints "Value of regex is nil":

NSString *responseString =   [[NSString alloc] initWithBytes:[responseDataForCrntUser bytes] length:responseDataForCrntUser.length encoding:NSUTF8StringEncoding];

NSError *error;
NSRegularExpression *regex = [NSRegularExpression regularExpressionWithPattern:@"(?<=badgeCount>)(?:[^])*?(?=</badgeCount)" options:0 error:&error];
if (regex != nil) {
    NSTextCheckingResult *firstMatch = [regex firstMatchInString:responseString options:0 range:NSMakeRange(0, [responseString length])];
    NSLog(@"NOT NIL");
    if (firstMatch) {
        NSRange accessTokenRange = [firstMatch rangeAtIndex:1];
        NSString *value = [urlString substringWithRange:accessTokenRange];
        NSLog(@"Value: %@", value);
    }
}
else
    NSLog(@"Value of regex is nil");

If you could provide sample code that would be much appreciated.

NOTE: I don't want to use NSXMLParser.

No need of NSXMLParser for extracting just a couple of values ... I did got the needed Regular Expression "(?<=badgeCount>)(?:[^])*?(?= — Prazi, Oct 05 '11 at 12:31
Edit your question to include the code you tried, and explain exactly what is not working about it. — Mat, Oct 05 '11 at 12:38

score 18 · Accepted Answer · answered Oct 05 '11 at 12:49

18

Example:

NSString *xml = @"<?xml version=\"1.0\" encoding=\"UTF-8\" standalone=\"yes\"?><badgeCount>6</badgeCount><rank>2</rank><screenName>myName</screenName>";
NSString *pattern = @"<badgeCount>(\\d+)</badgeCount>";

NSRegularExpression *regex = [NSRegularExpression
                                      regularExpressionWithPattern:pattern
                                      options:NSRegularExpressionCaseInsensitive
                                      error:nil];
NSTextCheckingResult *textCheckingResult = [regex firstMatchInString:xml options:0 range:NSMakeRange(0, xml.length)];

NSRange matchRange = [textCheckingResult rangeAtIndex:1];
NSString *match = [xml substringWithRange:matchRange];
NSLog(@"Found string '%@'", match);

NSLog output:

Found string '6'

answered Oct 05 '11 at 12:49

zaph

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If I want to get the value "myName" between tag do I need to create new regular expression or could I do it in the same. – Prazi Oct 05 '11 at 12:57
1

It would require a new regex because "\d+" specifies one or more digits. For a name you will need something like "\S+" (if there are no spaces in the name). There is a more general regex that should work in either case: @"([^", that says anything up to the " – zaph Oct 05 '11 at 13:05
Thanks for all your help. Much appreciated. .... So that means I need two separate patterns 1.([^ for getting badgeCount 2.([^ for getting screenName. – Prazi Oct 05 '11 at 13:08
Yes because the surrounding text is different. – zaph Oct 05 '11 at 13:12

score 4 · Answer 2 · edited May 12 '21 at 20:44

To do it in swift 3.0

func getMatchingValueFrom(strXML:String, tag:String) -> String {
    let pattern : String = "<"+tag+">(.*?)</"+tag+">" // original didn't work: "<"+tag+">(\\d+)</"+tag+">"
    let regexOptions = NSRegularExpression.Options.caseInsensitive
    
    do {
        let regex = try NSRegularExpression(pattern: pattern, options: regexOptions)
        let textCheckingResult : NSTextCheckingResult = regex.firstMatch(in: strXML, options: NSRegularExpression.MatchingOptions(rawValue: UInt(0)), range: NSMakeRange(0, strXML.count))!
        let matchRange : NSRange = textCheckingResult.range(at: 1)
        let match : String = (strXML as NSString).substring(with: matchRange)
        return match
    } catch {
        print(pattern + "<-- not found in string -->" + strXML )
        return ""
    }
}

P.S : This is corresponding swift solution of @zaph's solution in obj-c

`"(\\d+)"+tag+">"` did not work for me, I had to use `"(.*?)"+tag+">"`. — Alejandro Cotilla, Oct 21 '18 at 15:37

NSRegularExpression to extract text between two XML tags

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