How to disallow special characters but allow Asian/Middle Eastern characters in a UITextField

Question

I am using a UITextField for users to enter usernames, and would like to restrict special characters except for periods and underscores. I was initially set on using the solution from this SO question , until I realized that I do not want to restrict to only alpha-numeric characters, but also allow Asian and Middle Eastern languages characters as well. Is there a way that I would be able to accomplish this?

Thanks!

Update:

Per rmaddy's suggestion, here is what I am presently using:

- (BOOL)userNameIsAcceptable: (NSString *)userNameInputted
{
    NSCharacterSet *userNameAcceptedInput = [[NSCharacterSet alphanumericCharacterSet] invertedSet];
    NSString *filteredUserName = [[userNameInputted componentsSeparatedByCharactersInSet:userNameAcceptedInput] componentsJoinedByString:@""];
    NSLog(@"The filtered result %@", filteredUserName);

    return [userNameAcceptedInput isEqual:filteredUserName];
}

Answer 1

使用其他问题的解决方案，但不使用固定字母构建字符集，而是使用标准NSCharacterSet alphanumericCharacterSet 。

Answer 2

Maybe testing unicode chars from strings manually in loop against ranges containing unicode sets you need? I did quick check, and it seems that unicode sets of Japanese letters are usually densely packed, except some special characters - I've looked here http://www.rikai.com/library/kanjitables/kanji_codes.unicode.shtml but I guess similar should be valid to other languages as well.