Filtering characters entered into a UITextField

Question

I have a UITextField in my application. I\'d like to restrict the set of characters that can be can be entered into the field to a set that I have defined. I could filter th

Answer 1

This is what I use to restrict the user to uppercase A-Z. Adjust the regex variable according to taste:

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

    NSString* regex = @"[^A-Z]";
    return ([string rangeOfString: regex
                      options:NSRegularExpressionSearch].location == NSNotFound);
};