NSRegularExpression to validate URL - iphone

Question

I found this regular expression on a website. It is said to be the best URL validation expression out there and I agree. Diego Perini created it.
The problem I am facing is when trying to use it with objective-C to detect URLs on strings. I have tried using options like NSRegularExpressionAnchorsMatchLines, NSRegularExpressionIgnoreMetacharacters and others, but still no luck.
Is the expression not well formatted for Objective-C? Am I missing something? Any ideas?
I have tried John Gruber's regex, also, but it fails with some invalid URLs.
Regular Expression Explanation of expression
^ match at the beginning
//Protocol identifier
(?:
(?:https?|ftp http, https or ftp
):\\/\\/ ://
)? optional
// User:Pass authentication
(?:
^\\s+ non white spaces, 1 or more times
(?:
:^\\s* : non white spaces, 0 or more times, optionally
)?# #
)? optional
//Private IP Addresses ?! Means DO NOT MATCH ahead. So do not match any of the following
(?:
(?!10 10 10.0.0.0 - 10.999.999.999
(?:
\\.\\d{1,3} . 1 to 3 digits, three times
){3}
)
(?!127 127 127.0.0.0 - 127.999.999.999
(?:
\\.\\d{1,3} . 1 to 3 digits, three times
){3}
)
(?!169\\.254 169.254 169.254.0.0 - 169.254.999.999
(?:
\\.\\d{1,3} . 1 to 3 digits, two times
){2}
)
(?!192\\.168 192.168 192.168.0.0 - 192.168.999.999
(?:
\\.\\d{1,3} . 1 to 3 digits, two times
){2}
)
(?!172\\. 172. 172.16.0.0 - 172.31.999.999
(?:
1[6-9] 1 followed by any number between 6 and 9
| or
2\\d 2 and any digit
| or
3[0-1] 3 followed by a 0 or 1
)
(?:
\\.\\d{1,3} . 1 to 3 digits, two times
){2}
)
//First Octet IPv4 // match these. Any non network or broadcast IPv4 address
(?:
[1-9]\\d? any number from 1 to 9 followed by an optional digit 1 - 99
| or
1\\d\\d 1 followed by any two digits 100 - 199
| or
2[01]\\d 2 followed by any 0 or 1, followed by a digit 200 - 219
| or
22[0-3] 22 followed by any number between 0 and 3 220 - 223
)
//Second and Third Octet IPv4
(?:
\\. .
(?:
1?\\d{1,2} optional 1 followed by any 1 or two digits 0 - 199
| or
2[0-4]\\d 2 followed by any number between 0 and 4, and any digit 200 - 249
| or
25[0-5] 25 followed by any numbers between 0 and 5 250 - 255
)
){2} two times
//Fourth Octet IPv4
(?:
\\. .
(?:
[1-9]\\d? any number between 1 and 9 followed by an optional digit 1 - 99
| or
1\\d\\d 1 followed by any two digits 100 - 199
| or
2[0-4]\\d 2 followed by any number between 0 and 4, and any digit 200 - 249
| or
25[0-4] 25 followed by any number between 0 and 4 250 - 254
)
)
//Host name
| or
(?:
(?:
[a-z\u00a1-\uffff0-9]+-? any letter, digit or character one or more times with optional -
)* zero or more times
[a-z\u00a1-\uffff0-9]+ any letter, digit or character one or more times
)
//Domain name
(?:
\\. .
(?:
[a-z\u00a1-\uffff0-9]+-? any letter, digit or character one or more times with optional -
)* zero or more times
[a-z\u00a1-\uffff0-9]+ any letter, digit or character one or more times
)* zero or more times
//TLD identifier
(?:
\\. .
(?:
[a-z\u00a1-\uffff]{2,} any letter, digit or character more than two times
)
)
)
//Port number
(?:
:\\d{2,5} : followed by any digit, two to five times, optionally
)?
//Resource path
(?:
\\/[^\\s]* / followed by an optional non space character, zero or more times
)? optional
$ match at the end
EDIT
I think I forgot to say that I am using the expression in the following code: (partial code)
NSError *error = NULL;
NSRegularExpression *detector = [NSRegularExpression regularExpressionWithPattern:[self theRegularExpression] options:0 error:&error];
NSArray *links = [detector matchesInString:theText options:0 range:NSMakeRange(0, theText.length)];

Answer 1

^(?i)(?:(?:https?|ftp):\\/\\/)?(?:\\S+(?::\\S*)?#)?(?:(?:[1-9]\\d?|1\\d\\d|2[01]\\d|22[0-3])(?:\\.(?:1?\\d{1,2}|2[0-4]\\d|25[0-5])){2}(?:\\.(?:[1-9]\\d?|1\\d\\d|2[0-4]\\d|25[0-4]))|(?:(?:[a-z\\u00a1-\\uffff0-9]+-?)*[a-z\\u00a1-\\uffff0-9]+)(?:\\.(?:[a-z\\u00a1-\\uffff0-9]+-?)*[a-z\\u00a1-\\uffff0-9]+)*(?:\\.(?:[a-z\\u00a1-\\uffff]{2,})))(?::\\d{2,5})?(?:\\/[^\\s]*)?$
Is the best URL validation regular expression I found and it is explained on my question. It is already formatted to work on Objective-C. However, using it with NSRegularExpression gave me all sorts of problems, including my app crashing. RegexKitLite had no problems handling it. I do not know if it is a size limitation or some flag not being set.
My final code looked like:
//First I take the string and put every word in an array, then I match every word with the regular expression
NSArray *splitIntoWordsArray = [textToMatch componentsSeparatedByCharactersInSet:[NSCharacterSet whitespaceAndNewLineCharacterSet]];
NSMutableString *htmlString = [NSMutableString stringWithString:textToMatch];
for (NSString *theText in splitIntoWordsArray){
NSEnumerator *matchEnumerator = [theText matchEnumeratorWithRegex:theRegularExpressionString];
for (NSString *temp in matchEnumerator){
[htmlString replaceOccurrencesOfString:temp withString:[NSString stringWithFormat:#"%#", temp, temp] options:NSLiteralSearch range:NSMakeRange(0, [htmlString length])];
}
}
[htmlString replaceOccurrencesOfString:#"\n" withString:#"<br />" options:NSLiteralSearch range:NSMakeRange(0, htmlString.length)];
//embed the text on a webView as HTML
[webView loadHTMLString:[NSString stringWithFormat:embedHTML, [mainFont fontName], [mainFont pointSize], htmlString] baseURL:nil];
The result: a UIWebView with some embedded HTML, where URLs and emails are clickable. Do not forget to set dataDetectorTypes = UIDataDetectorTypeNone
You can also try
NSError *error = NULL;
NSRegularExpression *expression = [NSRegularExpression regularExpressionWithPattern:#"(?i)(?:(?:https?):\\/\\/)?(?:\\S+(?::\\S*)?#)?(?:(?:[1-9]\\d?|1\\d\\d|2[01]\\d|22[0-3])(?:\\.(?:1?\\d{1,2}|2[0-4]\\d|25[0-5])){2}(?:\\.(?:[1-9]\\d?|1\\d\\d|2[0-4]\\d|25[0-4]))|(?:(?:[a-z\\u00a1-\\uffff0-9]+-?)*[a-z\\u00a1-\\uffff0-9]+)(?:\\.(?:[a-z\\u00a1-\\uffff0-9]+-?)*[a-z\\u00a1-\\uffff0-9]+)*(?:\\.(?:[a-z\\u00a1-\\uffff]{2,})))(?::\\d{2,5})?(?:\\/[^\\s]*)?" options:NSRegularExpressionCaseInsensitive error:&error];
if (error)
NSLog(#"error");
NSString *someString = #"This is a sample of a sentence with a URL http://. http://.. http://../ http://? http://?? http://??/ http://# http://-error-.invalid/ http://-.~_!$&'()*+,;=:%40:80%2f::::::#example.com within it.";
NSRange range = [expression rangeOfFirstMatchInString:someString options:NSMatchingCompleted range:NSMakeRange(0, [someString length])];
if (!NSEqualRanges(range, NSMakeRange(NSNotFound, 0))){
NSString *match = [someString substringWithRange:range];
NSLog(#"%#", match);
}
else {
NSLog(#"no match");
}
Hope it helps somebody in the future
The regular expression will sometimes cause the application to hang, so I decided to use gruber's regular expression modified to recognize url without protocol or the www part:
(?i)\\b((?:[a-z][\\w-]+:(?:/{1,3}|[a-z0-9%])|www\\d{0,3}[.]|[a-z0-9.\\-]+[.][a-z]{2,4}/?)(?:[^\\s()<>]+|\\(([^\\s()<>]+|(\\([^\\s()<>]+\\)))*\\))*(?:\\(([^\\s()<>]+|(\\([^\\s()<>]+\\)))*\\)|[^\\s`!()\\[\\]{};:'\".,<>?«»“”‘’])*)

Answer 2

Am I missing something?
You're missing the built-in stuff to do this for you. There's a handy object called NSDataDetector. You create it to look for certain data "types" (like, say, NSTextCheckingTypeLink), then ask it for its -matchesInString:options:range:.
Here's an earlier answer of mine showing how to use it.