Unable to use backspace key to delete a character from a textfield in iOS

Question

I am implementing the following delegate method for UITextField:

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

         NSString *integerPart = [textField.text componentsSeparatedByString:@"."][0];
         NSString *decimalPart = [textField.text componentsSeparatedByString:@"."][1];

         if ([integerPart length] > 8 || [decimalPart length] > 5) {
             return NO;//this clause is always called.
         }
...
}

I am trying to limit the number of digits entered in the textField to 6. The problem I have is that if I enter a number with 6 digits after the decimal, and then try to press the backspace key on my device to delete the numbers, or need to make a correction inside the number, I'm unable to.

The reason is that whenever it comes to this point in my code, it notices that I have already entered 6 digits after the decimal (which is correct), and thus, nullifies my backspace key entry. How do I maintain this limit of 6 digits after the decimal place, AND allow for editing of the number after reaching this limit?

Answer 1

I haven't had a chance to test this, but according to this answer, string should be empty when a backspace is entered (which makes sense). So you should be able to do this.

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

         // Always allow a backspace
         if ([string isEqualToString:@""]) {
              return YES;
         }

         // Otherwise check lengths
         NSString *integerPart = [textField.text componentsSeparatedByString:@"."][0];
         NSString *decimalPart = [textField.text componentsSeparatedByString:@"."][1];

         if ([integerPart length] > 8 || [decimalPart length] > 5) {
             return NO;//this clause is always called.
         }

         return YES;
}