Check NSString for special characters

cocoa nsstring special-characters
Michael picture Michael · Feb 19, 2010 · Viewed 42.3k times · Source

I want to check an NSString for special characters, i.e. anything except a-z, A-Z and 0-9.

I don't need to check how many special characters are present, or their positions, I just need to know whether a particular string contains any or not. If it does, then I want to be able to display "Error!", or something similar.

For example, jHfd9982 is OK but asdJh992@ is not.

Also, letters with accents, diacritics, etc. should not be allowed.

How would I go about this?

Thanks!

Michael

Answer

Dave DeLong picture Dave DeLong · Feb 19, 2010 
NSCharacterSet * set = [[NSCharacterSet alphanumericCharacterSet] invertedSet];

if ([aString rangeOfCharacterFromSet:set].location != NSNotFound) {
  NSLog(@"This string contains illegal characters");
}

You could also use a regex (this syntax is from RegexKitLite: http://regexkit.sourceforge.net ):

if ([aString isMatchedByRegex:@"[^a-zA-Z0-9]"]) {
  NSLog(@"This string contains illegal characters");
}

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