activity_main.xml

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

    <com.pivincii.blogging.CustomView
        android:layout_width="match_parent"
        android:layout_height="match_parent"/>

</LinearLayout>

MainActivity.kt

package com.pivincii.blogging

import android.os.Bundle

class MainActivity : ActivityResultObservableActivity() {

    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(R.layout.activity_main)
    }

}