Resize a UIScrollview when the keyboard is shown based on the overlap between the scroll view and keyboard frame

ResizeScrollViewWithKeyboard.m

- (void) keyboardWillChangeFrame:(NSNotification *)notification {
    CGRect originalKeyboardFrame = [[[notification userInfo] objectForKey:UIKeyboardFrameEndUserInfoKey] CGRectValue];
    CGRect keyboardFrame = [[[UIApplication sharedApplication] keyWindow] convertRect:originalKeyboardFrame toView:self];
    CGFloat keyboardHeight = CGRectIntersection(keyboardFrame, self.contentScrollView.frame).size.height;
    
    [UIView animateWithDuration:[notification.userInfo[UIKeyboardAnimationDurationUserInfoKey] floatValue] delay:0 options:[notification.userInfo[UIKeyboardAnimationCurveUserInfoKey] integerValue] animations:^{
        self.contentScrollView.scrollIndicatorInsets = UIEdgeInsetsMake(0, 0, keyboardHeight, 0);
        self.contentScrollView.contentInset = UIEdgeInsetsMake(0, 0, keyboardHeight, 0);
    } completion:nil];
}