Autolayout Issue with growing UITextView above keyboard - ios

Question

I have a UIViewController with a main view. Within that view I have a red UIView that has a UITextView inside, that I would like to grow vertically when text is written. I'm able to have this effectively done if the redView initially starts somewhere in the middle of the screen and doesn't move based on the keyboard popping up by just modifying the UITextViewHeightConstraint that I made.
-(void)textViewDidChange:(UITextView *)textView {
[self.textView setScrollEnabled:NO];
CGSize newSize = [textView sizeThatFits:CGSizeMake(textView.frame.size.width, 999)];
if (newSize.height > textView.frame.size.height) {
self.textViewHeight.constant = newSize.height;
}
}
When I dock the redView that includes the UITextView subview to the bottom of the screen, my code appropriately will bring the view above the keyboard nicely, using the following code:
-(void)adjustViewForKeyboardNotification:(NSNotification *)notification {
NSDictionary *notificationInfo = [notification userInfo];
CGRect finalKeyboardFrame = [[notificationInfo objectForKey:UIKeyboardFrameEndUserInfoKey] CGRectValue];
//Get AnimationCurve and AnimationDuration for keyboard popping up.
UIViewAnimationCurve animationCurve = (UIViewAnimationCurve) [[notificationInfo objectForKey:UIKeyboardAnimationCurveUserInfoKey] integerValue];
NSTimeInterval animationDuration = [[notificationInfo objectForKey:UIKeyboardAnimationDurationUserInfoKey] doubleValue];
finalKeyboardFrame = [self.view convertRect:finalKeyboardFrame fromView:self.view.window];
CGRect textBarFrame = self.redView.frame;
textBarFrame.origin.y = finalKeyboardFrame.origin.y-textBarFrame.size.height;
[UIView beginAnimations:nil context:nil];
[UIView setAnimationDuration:animationDuration];
[UIView setAnimationCurve:animationCurve];
[UIView setAnimationBeginsFromCurrentState:YES];
self.redView.frame = textBarFrame;
[UIView commitAnimations];
}
However, when I start typing and it comes time for the UITextView to expand, the redView is sent back down and is docked to the bottom of the screen (under the keyboard) - where it then expands vertically as I would have liked. I've tried adjusting the constraints in many different ways but haven't found a solution. I've tried setting the frame of the redView manually but that doesn't seem to work either (likely because of auto layout being enabled).
Any advice or tips would be greatly appreciated!