Example of Instagram-Like Navigation about android-extensions

[tunjid]

@Minification
The root function is called only once; when the tab is visited for the the first time. After that, tapping on a previously visited tab will just show the fragment returned by the root function previously.

    override val navigator: MultiStackNavigator by multiStackNavigationController(
            tabs.size,
            R.id.content_container,
            RouteFragment.Companion::newInstance // Will be called once for each index
    )

As far as inner fragments go, their state will be preserved automatically as the FragmentManager takes care of it. If you wanted to show a different fragment at the root of each index, like with Instagram, you could do

    override val navigator: MultiStackNavigator by multiStackNavigationController(
            4,
            R.id.content_container,
            { index -> 
                when(index) {
                0 -> HomeFragment()
                1 -> ExploreFragment()
                2 -> ActivityFragment()
                3 -> ProfileFragment()
            }
    )

Within each inner fragment, if you wanted to go deeper into the tab, you can just get an instance of the navigator and push the new fragment like so:

class HomeFragment {
        private val navigator by activityNavigatorController<MultiStackNavigator>()

    fun goToPost(post: Post) {
        navigator.push(PostFragment.newInstance(post)
    }
}

Hope that helps.

[Minification]

Hi,

thanks for you quick reply, I think I understood.

I'm not sure if there isn't a bug, though. Assume we are using the example you gave above and HomeFragment has a button which takes us to InnerHomeFragment. Now I perform the following actions:

1. Start app, i.e. HomeFragment
2. ExploreFragment
3. ActivityFragment
4. HomeFragment
5. Press button, i.e. go to InnerHomeFragment
6. ExploreFragment
7. ActivityFragment

And now we press the back button a few times. What happens is the following:

1. ExploreFragment
2. InnerHomeFragment
3. HomeFragment
4. App shuts down gracefully (i.e. without errors)

Instead of the last step, I would have expected ActivityFragment, then ExploreFragment, then HomeFragment to show and then the app to shut down gracefully upon another back button press.

Is this inteded behaviour?

[tunjid]

@Minification Ah is see what you mean. The implementation of this is in MultiStackVisitor in MultiStackNavigator.kt; the assumption was no tab can exist twice in the nav history which is exactly what Instagram does. This can be modified, but like in the post you referenced, "Instagram-like navigation" is what I was going for with this.

[Minification]

I see, I believe instagram mostly circumvents this by swipes and button clicks navigating to fragments/activities without a bottom navigation view.

Would it be possible to make the MultiStackVisitor a overridable component of MultiStackNavigator, such that one could implement other behaviours?

But I believe I can work around this and essentially get my app to work about the same way that instagram does, thanks for taking the time to reply to this thread.

[tunjid]

@Minification that can be done, but probably not till this weekend or the next. You can submit a PR for it with tests if you want, all you need to do is selectively call this line with some boolean flag and it should work: https://github.com/tunjid/Android-Extensions/blob/develop/navigation/src/main/java/com/tunjid/androidx/navigation/MultiStackNavigator.kt#L251

[tunjid]

@Minification done in #102