Check if NSString contains alphanumeric + underscore characters only

Question

I\'ve got a string that needs to be only a-z, 0-9 and _

How do I check if the input is valid? I\'ve tried this but it accepts letter like å,ä,ö,ø etc.

NS         


        

Answer 1

Some more easy way,

NSMutableCharacterSet *allowedSet = [NSMutableCharacterSet characterSetWithCharactersInString:@"_"];
[allowedSet formUnionWithCharacterSet:[NSCharacterSet alphanumericCharacterSet]];
NSCharacterSet *forbiddenSet = [allowedSet invertedSet];

It'll combine alphanumeric along with _underscore.

you can use it like,

NSRange r = [string rangeOfCharacterFromSet:forbiddenSet];
if (r.location != NSNotFound) {
  NSLog(@"the string contains illegal characters");
}

PS. example copied from @DaveDeLong example :)