How to retain state of views of orientation changes in Android Conductor?

Question

I am currently learning about the Conductor framework for Android and have a bit of a problem or misunderstanding of how it works.

I was under the impression that the method

setRetainViewMode(RetainViewMode.RETAIN_DETACH);

would save the states of the views in the controller. To test the behaviour, I added EditText views, entered a value in it and rotated the screen. I also added 2 views with onclick listeners attached, changing the background color onclick

The result of the test was that the EditText views maintained the state and preserved the entered values. But the 2 views, changed back to their original background color (none).

This is the behaviour of the views regardless on which RetainViewMode is set

I have this simple MainActivity (note: I'm writing in Kotlin):

    class MainActivity : AppCompatActivity() {

    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(R.layout.activity_main)
        var router: Router = Conductor.attachRouter(this, controller_container, savedInstanceState)
        if (!router.hasRootController()) {
            var t : TestController = TestController()
            t.retainViewMode = Controller.RetainViewMode.RETAIN_DETACH
            router.setRoot(RouterTransaction.with(t))
        }
    }

    companion object doTask {
        fun start(activity : Activity) {
            val intent = Intent(activity, MainActivity::class.java)
            activity.startActivity(intent)
        }
    }
}

And here is the the TestController:

    class TestController : BaseController() {

    var i : Int = 0
    var h : Int = 0

    override fun onViewBound(view: View) {
        view.a.setOnClickListener {
            i++
            if (i % 2 == 0) {
                view.a.setBackgroundColor(ContextCompat.getColor(applicationContext, R.color.white))
            } else {
                view.a.setBackgroundColor(ContextCompat.getColor(applicationContext, R.color.turtle_green))
            }
        }

        view.b.setOnClickListener {
            h++
            if (h % 2 == 0) {
                view.b.setBackgroundColor(ContextCompat.getColor(applicationContext, R.color.white))
            } else {
                view.b.setBackgroundColor(ContextCompat.getColor(applicationContext, R.color.blue_light))
            }
        }
    }

    override fun inflateView(inflater: LayoutInflater, container: ViewGroup): View {
        return inflater.inflate(R.layout.controller_layout_test, container, false)
    }

}

And xml layout file controller_layout_test:

<?xml version="1.0" encoding="utf-8"?>
<FrameLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent">
    <requestFocus></requestFocus>

    <ImageView
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:src="@drawable/logo_simple"/>

    <ScrollView
        android:layout_width="match_parent"
        android:layout_height="match_parent">

        <LinearLayout
            android:layout_width="300dp"
            android:layout_height="wrap_content"
            android:orientation="vertical"
            android:layout_margin="30dp"
            android:layout_gravity="center"
            android:background="@color/transparent50p"
            android:padding="20dp">

            <EditText
                android:id="@+id/gt"
                android:layout_width="match_parent"
                android:layout_height="40dp"
                android:layout_gravity="center"
                android:layout_marginTop="10dp"
                android:padding="6dp"
                android:background="@color/white_transparent50p"/>

                />

            <EditText
                android:id="@+id/erergeargf"
                android:layout_width="match_parent"
                android:layout_height="40dp"
                android:layout_gravity="center"
                android:layout_marginTop="10dp"
                android:padding="6dp"
                android:background="@color/white_transparent50p"/>

            <View
                android:id="@+id/a"
                android:layout_width="50dp"
                android:layout_height="50dp"
                android:layout_margin="5dp"
                android:layout_gravity="center"></View>

            <View
                android:id="@+id/b"
                android:layout_width="50dp"
                android:layout_height="50dp"
                android:layout_margin="5dp"
                android:layout_gravity="center"></View>
        </LinearLayout>

    </ScrollView>

</FrameLayout>

activity_main xml layout looks like this:

<?xml version="1.0" encoding="utf-8"?>
<android.support.design.widget.CoordinatorLayout
xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:fitsSystemWindows="true"
tools:context="dk.minreklame.minetilbud_v2.MainActivity">

<android.support.design.widget.AppBarLayout
    android:layout_width="match_parent"
    android:layout_height="wrap_content">

    <android.support.v7.widget.Toolbar
        android:id="@+id/toolbar"
        android:layout_width="match_parent"
        android:layout_height="?attr/actionBarSize"
        android:theme="@style/ThemeOverlay.AppCompat.Dark.ActionBar"
        />

</android.support.design.widget.AppBarLayout>

<com.bluelinelabs.conductor.ChangeHandlerFrameLayout
    android:id="@+id/controller_container"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    app:layout_behavior="@string/appbar_scrolling_view_behavior"
    />

</android.support.design.widget.CoordinatorLayout>

Answer 1

As your views have references to the host Activity, they will never be retained across orientation changes. That would cause a memory leak. The docs on RETAIN_DETACH state:

The Controller will retain its reference to its view when detached, but will still release the reference when a config change occurs.