Validate e-mail address

The method that I am using, uses NSRegularExpression. Taken directly from the Apple website:

The NSRegularExpression class is used to represent and apply regular expressions to Unicode strings. An instance of this class is an immutable representation of a compiled regular expression pattern and various option flags. The pattern syntax currently supported is that specified by ICU. The ICU regular expressions are described at http://userguide.icu-project.org/strings/regexp .

The fundamental matching method for NSRegularExpression is a Block iterator method that allows clients to supply a Block object which will be invoked each time the regular expression matches a portion of the target string. There are additional convenience methods for returning all the matches as an array, the total number of matches, the first match, and the range of the first match.

So, here it is:

- (BOOL) validEmail:(NSString*) emailString 

{

    if([emailString length]==0)

   {

        return NO;

    }

    NSString *regExPattern = @"[A-Z0-9a-z._%+-]+@[A-Za-z0-9.-]+\\.[A-Za-z]{2,4}";

    NSRegularExpression *regEx = [[NSRegularExpression alloc] initWithPattern:regExPattern options:NSRegularExpressionCaseInsensitive error:nil];

    NSUInteger regExMatches = [regEx numberOfMatchesInString:emailString options:0 range:NSMakeRange(0, [emailString length])];

    NSLog(@"%i", regExMatches);

    if (regExMatches == 0) 

    {

        return NO;

    } else 

    {

        return YES;

    }

}