iphone - regex to find hashtags in tweet not working correctly -

i trying build function find hashtags in tweest. , surround them html <a> tag. can link them. here do.

nserror* error = nil;  nsregularexpression* regex = [nsregularexpression regularexpressionwithpattern:@"(?:\\s|\\a)[##]+([a-za-z0-9-_]+)" options:0 error:&error]; nsarray* matches = [regex matchesinstring:tweettext options:0 range:nsmakerange(0, [tweettext length])]; ( nstextcheckingresult* match in matches ) {     nsstring* matchtext = [tweettext substringwithrange:[match range]];     nsstring *matchtext2 = [matchtext stringbytrimmingcharactersinset:[nscharacterset whitespacecharacterset]];     nsstring *search = [matchtext2 stringbyreplacingoccurrencesofstring:@"#"                                                             withstring:@""];     nsstring *searchhtml= [nsstring stringwithformat:@"<a href='https://twitter.com/search?q=%%23%@'>%@</a>",search,matchtext];     tweettext = [tweettext stringbyreplacingoccurrencesofstring:matchtext                                                     withstring:searchhtml];     nslog(@"match: %@", tweettext); } 

before execute function, tweettext looped through function find url. tweet can contain following. <a href='http://google.be' target='_blank'>http://google.be</a>

now places tag around other links , not around hashtags.

can me this.

tip

i trying transform following java code obj-c

  string patternstr = "(?:\\s|\\a)[##]+([a-za-z0-9-_]+)"      pattern pattern = pattern.compile(patternstr)      matcher matcher = pattern.matcher(tweettext)      string result = "";       // search hashtags      while (matcher.find()) {      result = matcher.group();      result = result.replace(" ", "");      string search = result.replace("#", "");      string searchhtml="<a href='http://search.twitter.com/search?q=" + search + "'>" + result + "</a>"      tweettext = tweettext.replace(result,searchhtml);      } 

edit

gers, kijken er al naar uit! “@gerspardoel: zitten in belgië straks naar genk!!<a href='<a href<a href='https://twitter.com/search?q=%23='http'>='http</a>s://twitter.com/search?q=%23https:/'>https:/</a>/twitter.com/search?q=%23engaan'> #engaan</a>” #gos12 #genk #fb 

the problem you're modifying tweettext variable (tweettext = ...) you're looping through matches. imagine happens next time code enters loop? substringwithrange not work since created on original string. try rectify problem , if you're unable it, check solution here: http://pastebin.com/dyqqtrza

edit: adding solution here:

nserror* error = nil;  nsregularexpression* regex = [nsregularexpression regularexpressionwithpattern:@"(?:\\s|\\a)[##]+([a-za-z0-9-_]+)" options:0 error:&error]; nsarray* matches = [regex matchesinstring:tweettext options:0 range:nsmakerange(0, [tweettext length])]; nsstring* processedstring = [[tweettext copy] autorelease]; ( nstextcheckingresult* match in matches ) {     nsstring* matchtext = [tweettext substringwithrange:[match range]];     nsstring *matchtext2 = [matchtext stringbytrimmingcharactersinset:[nscharacterset whitespacecharacterset]];     nsstring *search = [matchtext2 stringbyreplacingoccurrencesofstring:@"#"                                                             withstring:@""];     nsstring *searchhtml= [nsstring stringwithformat:@"<a href='https://twitter.com/search?q=%%23%@'>%@</a>",search,matchtext];     processedstring = [processedstring stringbyreplacingoccurrencesofstring:matchtext                                                                  withstring:searchhtml];     nslog(@"match: %@", processedstring); }