Set up the FlutterActivity in AndroidManifest.xml

In AndroidManifest.xml, set the theme of
FlutterActivity to the launch theme. Then,
add a metadata element to the desired FlutterActivity
to instruct Flutter to switch from the launch theme
to the normal theme at the appropriate time.

<activity

android:name=

".MyActivity"

android:theme=

"@style/LaunchTheme"

//

...

<meta-data

android:name=

"io.flutter.embedding.android.NormalTheme"

android:resource=

"@style/NormalTheme"

/>

<intent-filter>

<action

android:name=

"android.intent.action.MAIN"

/>

<category