URL Validation function improving - objective-c

Question

i use this function to check if an URL is valid or not. it works for most of the cases, but here the following URL it return that is not Valid!
http://www.iphonedevsdk.com/forum/iphone-sdk-development/11841-stringbytrimmingcharactersinset.html
what can i do to improve the regular expression of my function that it will cover all URL types?
- (BOOL) urlIsValiad: (NSString *) url
{
NSString *regex =
#"(http|https)://((\\w)*|([0-9]*)|([-|_])*)+([\\.|/]((\\w)*|([0-9]*)|([-|_])*))+";
NSPredicate *regextest = [NSPredicate predicateWithFormat:#"SELF MATCHES %#", regex];
if ([regextest evaluateWithObject: url] == YES) {
NSLog(#"URL is valid!");
} else {
NSLog(#"URL is not valid!");
}
return [regextest evaluateWithObject:url];
}

Answer 1

This would be my attempt:
((?:http|https)://)?(?:www\\.)?[\\w\\d\\-_]+\\.\\w{2,3}(\\.\\w{2})?(/(?<=/)(?:[\\w\\d\\-./_]+)?)?
EDIT
Added in a back-reference (?<=/)for extra specificity
EDIT 2
Added optional search for country name in URL (eg www.google.com.in)

Answer 2

Try to change the *regex = line with following.
NSString *regex = "(http|ftp|https)://[\w-_]+(.[\w-_]+)+([\w-.,#?^=%&:/~+#]* [\w-\#?^=%&/~+#])?"

Answer 3

Well, I found something on Microsoft site and with slight changes it's the best expression so far:
#"(?:[A-Za-z0-9!#$%\\&'*+/=?\\^_`{|}~-]+(?:\\.[A-Za-z0-9!#$%\\&'*+/=?\\^_`{|}"
#"~-]+)*|\"(?:[\\x01-\\x08\\x0b\\x0c\\x0e-\\x1f\\x21\\x23-\\x5b\\x5d-\\"
#"x7f]|\\\\[\\x01-\\x09\\x0b\\x0c\\x0e-\\x7f])*\")#(?:(?:[A-Za-z0-9](?:[A-Za-"
#"z0-9-]*[A-Za-z0-9])?\\.)+[A-Za-z0-9](?:[A-Za-z0-9-]*[A-Za-z0-9])?|\\[(?:(?:25[0-5"
#"]|2[0-4][0-9]|[01]?[0-9][0-9]?)\\.){3}(?:25[0-5]|2[0-4][0-9]|[01]?[0-"
#"9][0-9]?|[A-Za-z0-9-]*[A-Za-z0-9]:(?:[\\x01-\\x08\\x0b\\x0c\\x0e-\\x1f\\x21"
#"-\\x5a\\x53-\\x7f]|\\\\[\\x01-\\x09\\x0b\\x0c\\x0e-\\x7f])+)\\])";

Answer 4

Old thread but I think my amendments may be helpful to someone else landing here:
I didn't like to check only for a "www" as a hostname, nowadays we may encounter different hostnames... Thus I extended the Regex with:
"((?:http|https)://)?(?:[A-Za-z0-9]{1,25}\\.)?[\\w\\d\\-_]+\\.\\w{2,3}(\\.\\w{2})?(/(?<=/)(?:[\\w\\d\\-./_]+)?)?"

Answer 5

-(BOOL)validateUrl{
// NSString *urlRegEx = #"((?:http|https)://)?(www\\.)[\\w\\d\\-_]+\\.\\w{2,3}(\\.\\w{2})?(/(?<=/)(?:[\\w\\d\\-./_]+)?)?";
NSString *urlRegEx = #"((?:http|https)://)?(www\\.)[\\w\\d\\-_]+\\.\\w{2,3}(\\.\\w{2})?(/(?<=/)(?:[\\w\\d\\-./_]+)?)?";
NSPredicate *urlTest = [NSPredicate predicateWithFormat:#"SELF MATCHES %#", urlRegEx];
if ([urlTest evaluateWithObject: self] == YES) {
NSLog(#"URL is valid!");
} else {
NSLog(#"URL is not valid!");
}
return [urlTest evaluateWithObject:self];
}