androidx.core:core-splashscreen の雑サンプル

MainActivity.kt

class MainActivity : AppCompatActivity() {

    private val viewModel: MainViewModel by viewModels()

    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        val splashScreen = installSplashScreen() // ★ SplashScreenを適用
        setContentView(R.layout.activity_main)

        splashScreen.setKeepVisibleCondition {　 // ★　ここでtrueを返してる間はSplashScreenが表示されたまま
            viewModel.isReady().not()
        }
    }
}

themes.xml

<style name="Theme.AppSplashScreen" parent="Theme.SplashScreen">
    <item name="postSplashScreenTheme">@style/Theme.MyApplication</item> <!-- SplashScreen表示後のTheme -->
    <item name="windowSplashScreenAnimatedIcon">@mipmap/ic_launcher_round</item> <!-- SplashScreenアイコン -->
    <item name="windowSplashScreenBackground">@color/white</item> <!-- SplashScreenの背景 -->
</style>