Material Design checklist: hiding app bar on scroll?

Question

Per the new Android Material Design checklist:

http://android-developers.blogspot.com/2014/10/material-design-on-android-checklist.html

Where appr

Answer 1

Ref: https://material.io/develop/android/components/app-bars-bottom

hiding app bar on scroll:

<com.google.android.material.bottomappbar.BottomAppBar
    android:id="@+id/bottomAppBar"
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:layout_gravity="bottom"

    app:hideOnScroll="true"

    app:navigationIcon="@drawable/ic_menu_color_control_normal_24dp"
    app:navigationContentDescription="Navigation icon"
    android:fitsSystemWindows="true"
    />

Kotlin: programmatically

  bottomAppBar.hideOnScroll = true

Answer 2

Per Roman Nurik on Google+ (essentially what @tyczj mentioned)

https://plus.google.com/u/0/+RomanNurik/posts/3G8zYvN5oRC

It's not built in but relatively simple to implement. Just observe scrolling and animate the Y translation. Could also use the "quick return" sample +Nick Butcher​ and I published a few years ago

I believe that example referenced is: https://code.google.com/p/romannurik-code/source/browse/misc/scrolltricks

UPDATE: I also just discovered a great library that does this, along with some other great tricks https://github.com/ksoichiro/Android-ObservableScrollView