Check NSString for special characters

Question

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 p

Answer 1

This code allows only numbers in UITextField input.

- (BOOL)textField:(UITextField *)textField shouldChangeCharactersInRange:(NSRange)range replacementString:(NSString *)string {

    if ([string rangeOfCharacterFromSet:[[NSCharacterSet decimalDigitCharacterSet] invertedSet]].location != NSNotFound)
        return NO;
    else
        return YES;

}