How to validate an url on the iPhone

Question

In an iPhone app I am developing, there is a setting in which you can enter a URL, because of form & function this URL needs to be validated online as well as offline.

So far I haven't been able to find any method to validate the url, so the question is;

How do I validate an URL input on the iPhone (Objective-C) online as well as offline?

Answer 1

Hi, did you mean to check if what the user entered is a URL? It can be as simple as a regular expression, for example checking if the string contain www. (this is the way that yahoo messenger checks if the user status is a link or not)
Hope that help

Answer 2

I solved the problem using RegexKit, and build a quick regex to validate a URL;

NSString *regexString = @"(http|https)://((\\w)*|([0-9]*)|([-|_])*)+([\\.|/]((\\w)*|([0-9]*)|([-|_])*))+";
NSString *subjectString = brandLink.text;
NSString *matchedString = [subjectString stringByMatching:regexString];

Then I check if the matchedString is equal to the subjectString and if that is the case the url is valid :)

Correct me if my regex is wrong ;)

Answer 3

Thanks to this post, you can avoid using RegexKit. Here is my solution (works for iphone development with iOS > 3.0) :

- (BOOL) validateUrl: (NSString *) candidate {
    NSString *urlRegEx =
    @"(http|https)://((\\w)*|([0-9]*)|([-|_])*)+([\\.|/]((\\w)*|([0-9]*)|([-|_])*))+";
    NSPredicate *urlTest = [NSPredicate predicateWithFormat:@"SELF MATCHES %@", urlRegEx]; 
    return [urlTest evaluateWithObject:candidate];
}