Numberpad backspace not updating textField.text.length - iphone

Question

I'm currently formatting my a textfield in xcode, every 5th character I add a hyphen.
However I'm having alot of trouble I am currently wanting to check my textfields.text.length then once the length reaches 23 characters the submit button is press-able. So far this works where I have trouble is say if the user enters 23 characters and the button is press-able if the user decided to go back and delete one character there is nothing to update the new text length as I don't know how to catch the delete button of the numberpad... Dose anyone know how to do this?
- (BOOL)textField:(UITextField *)textField shouldChangeCharactersInRange:(NSRange)range replacementString:(NSString *)string {
NSString *separator = #"-";
int seperatorInterval = 5;
NSString *originalString = [regTextField.text stringByReplacingOccurrencesOfString:separator withString:#""];
if (![originalString isEqualToString:#""] && ![string isEqualToString:#""]) {
NSString *lastChar = [regTextField.text substringFromIndex:[regTextField.text length] - 1];
int modulus = [originalString length] % seperatorInterval;
[self validateTextFields];
if (![lastChar isEqualToString:separator] && modulus == 0) {
regTextField.text = [regTextField.text stringByAppendingString:separator];
}
}
[self validateTextFields];
return YES;
}
-(IBAction) validateTextFields {
if (regTextField.text.length >= 22){
[submitButton setEnabled:YES]; //enables submitButton
}
else {
[submitButton setEnabled:NO]; //disables submitButton
}
}

Answer 1

Try something like this:
- (BOOL)textView:(UITextView *)textView shouldChangeTextInRange:(NSRange)range replacementText:(NSString *)text
{
// Any new character added is passed in as the "text" parameter
if (!([text isEqualToString:#""] && range.length == 1) && [textView.text length] >=140 ) {
return NO;
}
// For any other character return TRUE so that the text gets added to the view
return YES;
}
Where the block:
([text isEqualToString:#""] && range.length == 1)
Is the check for the backspace.
Capturing the backspace on the Number Pad Keyboard