Web regex validation on Objective-C

Question

I've some regular expressions for the form fields validation.

I've an unit test to define the expected result

NSArray *suiteWebs = [NSArray arrayWithObjects:
                      @"http://webapp.stackoverflow.net",
                      @"http://webapp.stackoverflow.net/info.php",
                      @"http://www.stackoverflow.net",
                      @"http://www.stackoverflow.net/",
                      @"https://webapp.stackoverflow.net",
                      @"https://webapp.stackoverflow.net/info.php",
                      @"https://www.stackoverflow.net",
                      @"https://www.stackoverflow.net/"
                      @"webapp.stackoverflow.net",
                      @"webapp.stackoverflow.net/info.php",
                      @"www.stackoverflow.net",
                      @"www.stackoverflow.net/",
                      @"www.stack-overflow.com",
                      @"www.stackoverflow_.com",
                      @"www.stackover_flow.com",
                      nil];

NSArray *falseSuiteWebs = [NSArray arrayWithObjects:
                           @"ftp://webapp.stackoverflow.net",
                           @"http:/www.stackoverflow.net",
                           @"ftps://webapp.stackoverflow.net",
                           @"https:/www.stackoverflow.net",
                           nil];

for (NSString *web in suiteWebs) {
    NSLog(@"Validating web %@", web);
    STAssertTrue([TSAddEntityForm validateWeb:web withPatter:currentRegex], [NSString stringWithFormat:@"currentRegex web %@", web]);
}

for (NSString *web in falseSuiteWebs) {
    NSLog(@"Validating web %@", web);
    STAssertFalse([TSAddEntityForm validateWeb:web withPatter:currentRegex], [NSString stringWithFormat:@"currentRegex web %@", web]);
}

My actual regular expression is the next one:

NSString *webRegex4 = @"((http|https)://){0,1}((\\w)*|([0-9]*)|([\\-|_])*)+([\\.|/]((\\w)*|([0-9]*)|([\\-|_])*))+";

My problem are with the domains with - my regular expression don't validate it. For example the url www.stack-overflow.com is rejected

Any suggestions?

Thank you

Mikhail · Accepted Answer · 2013-02-20 13:32:18Z

2

May be this regexp would be better in your case (it's not ideal, but works for above suitable and bad samples):

(http(s)?://)?[\w-]+(\.[\w-]+)*\.\w{2,6}[/\w.-]*

It may begin from http:// or https://,

[\w-]+(\.[\w-]+)*\.\w{2,6} - describes domain

[/\w.-]* - folders and documents

edited Feb 20, 2013 at 13:32

answered Feb 20, 2013 at 13:01

Mikhail

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1 Comment

Iván Peralta Over a year ago

Thank you!! It's exactly what we need.

uchuugaka · Accepted Answer · 2013-02-20 13:37:17Z

1

In general, complex regular expressions are fool's gold. Use multiple passes with multiple regular expressions. Validate components of the URLs independently.

Complex regular expressions can be very powerful, but can also paint you into a fragile corner with something as open ended as URLs.

Also, if you're using Objective-C, it is easy to break things down with some of the facilities provided by NSURL. NSURL will also give you a good idea of what components of a URL you should look at. By using NSURL methods to extract components of the URLs, you can apply your regular expressions more carefully to each component.

CFURL is equally powerful.

answered Feb 20, 2013 at 13:37

uchuugaka

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2 Comments

Iván Peralta Over a year ago

Yep, it's a good point. But I prefer to find the complex regular expression in order to have the same validation pattern in the different platforms we have. Thanks!

uchuugaka Over a year ago

You can still break it into components and handle them on multiple platforms. This seems more like a regular expression question than a Objective-C question.

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