NSUInteger selectedIndex = [self.navigationView indexOfSelectedButton];

    BOOL directionRight = index > selectedIndex;

    UIViewController *currentController = self.viewControllers[selectedIndex];
    UIViewController *targetController = self.viewControllers[index];

    NSArray *allControllers = self.viewControllers;
    if (directionRight) {
        self.viewControllers = @[currentController, targetController];
    } else {
        self.viewControllers = @[targetController, currentController];
    }

    [self.collectionView reloadData];

    NSIndexPath *indexPath = [NSIndexPath indexPathForItem:!directionRight inSection:0];
    [self.collectionView scrollToItemAtIndexPath:indexPath atScrollPosition:UICollectionViewScrollPositionCenteredHorizontally animated:NO];
    [self.collectionView layoutIfNeeded];

    self.collectionViewAnimationFinishBlock = ^{
        self.collectionView.userInteractionEnabled = YES;
        self.viewControllers = allControllers;
        [self.collectionView reloadData];

        NSUInteger realIndexForTargetController = [self.viewControllers indexOfObject:targetController];
        NSIndexPath *realIndexPath = [NSIndexPath indexPathForItem:realIndexForTargetController inSection:0];
        [self.collectionView scrollToItemAtIndexPath:realIndexPath atScrollPosition:UICollectionViewScrollPositionCenteredHorizontally animated:NO];

        [self.navigationView setSelectedIndex:selectedIndex];
        UIViewController *controller = self.viewControllers[index];
        [self configureNavigationBarForController:controller];
    };

    self.collectionView.userInteractionEnabled = NO;
    indexPath = [NSIndexPath indexPathForItem:directionRight inSection:0];
    [self.collectionView scrollToItemAtIndexPath:indexPath atScrollPosition:UICollectionViewScrollPositionCenteredHorizontally animated:YES];