【ANDROID STUDIO】Life Cycle Scope

 package com.example.lifecyclescope

import androidx.appcompat.app.AppCompatActivity
import android.os.Bundle
import android.view.View
import androidx.lifecycle.lifecycleScope
import com.example.lifecyclescope.ui.main.MainFragment
import kotlinx.android.synthetic.main.main_activity.*
import kotlinx.coroutines.delay
import kotlinx.coroutines.launch

class MainActivity : AppCompatActivity() {

    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(R.layout.main_activity)
        if (savedInstanceState == null) {
            supportFragmentManager.beginTransaction()
                    .replace(R.id.container, MainFragment.newInstance())
                    .commitNow()
        }
        lifecycleScope.launch{
delay(5000)
            progressBar.visibility = View.VISIBLE
            delay(10000)
            progressBar.visibility = View.GONE

        }
    }
}

<?xml version="1.0" encoding="utf-8"?>
<FrameLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:id="@+id/container"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context=".MainActivity" >

    <ProgressBar
        android:id="@+id/progressBar"
        style="?android:attr/progressBarStyle"
        android:visibility="gone"
        android:layout_width="match_parent"
        android:layout_height="match_parent" />
</FrameLayout>