NSPredicate and Regex

objective-c regex nspredicate
Dave picture Dave · Mar 17, 2010 · Viewed 7.8k times · Source

Can someone please help me with using Regex with NSPredicate? 

NSString *regex = @"(?:[A-Za-z0-9])";
NSPredicate *pred = [NSPredicate predicateWithFormat:@"SELF MATCHES %@", regex];
if ([pred evaluateWithObject:mystring])
{
  //do something
}

testing the above wth mystring - qstring123 doesn't seem to work. I am expecting it to enter the if condition because it supposedly should match the regex.

Besides, I need a regex for alpha numberic allowing commas and spaces.

will this work?

@"(?:[A-Za-z0-9])*(?:,[A-sa-z0-9)*(?:\s[A-sa-s0-9])"

Please help.

Answer

Dave DeLong picture Dave DeLong · Mar 17, 2010

From my experimentation, it tries to match the regex against the entire string, and won't match inside a string.

Therefore, the regex [a-zA-Z0-9]+ works, but [a-zA-Z0-9] does not.

With that in mind, you may want to rework your comma-matching predicate, or use a more full-featured regex solution, like the amazingly awesome RegexKit and RegexKitLite.

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