TvOS UITabBarController detect tabbar shown/hidden

Question

Is there anyway to detect that the tabbar of a UITabBarController is going to appear or disappear? I want to make an animation simultaneously with the animation that shows/hides the tabbar.

I haven't find any way to detect this event. The property "hidden" of the tabbar is not an option because it changes its value once the animation has finished

Answer 1

The solution was to use the method in the view controller didUpdateFocusInContext:withAnimationCoordinator: with this code:

static NSString *kUITabBarButtonClassName = @"UITabBarButton";

NSString *prevFocusViewClassName = NSStringFromClass([context.previouslyFocusedView class]);
    NSString *nextFocusedView = NSStringFromClass([context.nextFocusedView class]);

    // The tabbar is going to disappear
    if ([prevFocusViewClassName isEqualToString:kUITabBarButtonClassName] &&
        ![nextFocusedView isEqualToString:kUITabBarButtonClassName]) {
        [self.view layoutIfNeeded];
        self.constraintScrollViewCenterY.constant -= self.tabBarController.tabBar.frame.size.height;

        [coordinator addCoordinatedAnimations:^{
            [self.view layoutIfNeeded];
        } completion:nil];
    // The tabbar is going to appear
    } else if (![prevFocusViewClassName isEqualToString:kUITabBarButtonClassName] &&
               [nextFocusedView isEqualToString:kUITabBarButtonClassName]) {
        [self.view layoutIfNeeded];
        self.constraintScrollViewCenterY.constant += self.tabBarController.tabBar.frame.size.height;

        [coordinator addCoordinatedAnimations:^{
            [self.view layoutIfNeeded];
        } completion:nil];
    }

where self.constraintScrollViewCenterY is a constraint related to the vertical alignment of the view I want to move according to the tabbar movement

Note: The use of class name (kUITabBarButtonClassName) instead of [... class] method is due to UITabBarButton is a private class