Question

I’m stuck on this problem for quite a while now and I couldn’t figure out a proper solution with the usual google search. I’m trying to evaluate the format of a string, more precisely I’m checking to see if the string is a Canadian postal code or not.

So I started with this regex, thanks to geeks with blogs

^[ABCEGHJKLMNPRSTVXY]{1}\d{1}[A-Z]{1} *\d{1}[A-Z]{1}\d{1}$

After that, I’ve created an instance of NSRegularExpression in such way:

NSRegularExpression *regex = [NSRegularExpression regularExpressionWithPattern:@"^[ABCEGHJKLMNPRSTVXY]{1}\\d{1}[A-Z]{1} *\\d{1}[A-Z]{1}\\d{1}$" options:NSRegularExpressionCaseInsensitive error:&error];

With added backslashes for escaping.

Then I made an NSPredicate with the regular expression

NSPredicate *regextest = [NSPredicate
                          predicateWithFormat:@"SELF MATCHES[cd] %@", regex];

And finally, I’m evaluating the string itself

[regextest evaluateWithObject:@"G2G 2S2"]

At that last line, an exception is thrown.

NSInvalidArgumentException Can’t create a regex expression from object

NSRegularExpression: 0x81e1bb0 ^[ABCEGHJKLMNPRSTVXY]{1}\d{1}[A-Z]{1}
*\d{1}[A-Z]{1}\d{1}$ 0x1.

I can’t figure it out =/ I tested the regex itself with a regex tester and it’s fine, and from what I checked with google that’s how a string evaluation should be done. I’m at lost here. Anyone have an idea?

Answer 1

In an NSPredicate the pattern is just a string, so this will work:

NSString *pattern = @"^[ABCEGHJKLMNPRSTVXY]{1}\\d{1}[A-Z]{1} *\\d{1}[A-Z]{1}\\d{1}$";

NSPredicate *regextest = [NSPredicate predicateWithFormat:@"SELF MATCHES[cd] %@", pattern];

BOOL result = [regextest evaluateWithObject:@"G2G 2S2"];

Oh, and I agree that the {1}-parts should be removed – they just add clutter.