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

How about this?

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

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

Note:

I am making all characters to lower case [string lowercaseString] so that you don't need to write in regex for captial/small letters.