AutoLayout UIScrollView adjustments with arbitrary keyboard sizes on iOS 8

AutoLayout_keyboard_iOS8.m

// If you're using Interface Builder, set your UITextView or UIScrollView bottom constraint to the bottom layout guide, constant=0, then create an IBOutlet for the constraint.
// If you're writing it in code, create that constraint programatically and make sure it's a @property.

- (void)viewDidAppear:(BOOL)animated
{
    [[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(keyboardDidShow:) name:UIKeyboardDidShowNotification object:nil];
    [[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(keyboardDidHide:) name:UIKeyboardDidHideNotification object:nil];
    
    // You're probably going to do this, but it's not actually part of the example
    _textView.delegate = self;
    [_textView becomeFirstResponder];
}

- (void)keyboardDidShow:(NSNotification *)notification
{
    [self scrollControlBarTo:notification up:YES];
}

-(void)keyboardDidHide:(NSNotification *)notification
{
    [self scrollControlBarTo:notification up:NO];
}

- (void)scrollControlBarTo:(NSNotification *)notification up:(BOOL)up
{
    [_keyboardControlsBar layoutIfNeeded];
    CGRect keyboardBounds;
    [[notification.userInfo objectForKey:UIKeyboardFrameEndUserInfoKey] getValue:&keyboardBounds];
    
    [UIView animateWithDuration:0.15 // you might want to play with the timing here, or get really fancy and retrieve it from userInfo.
                     animations:^{
                         // This is the @property you created in the comments up top.
                         _keyboardControlsBarBottomConstraint.constant = (up) ? keyboardBounds.size.height : 0;
                         [self.view layoutIfNeeded];
                     }];
}