Why my flutter app showing white screen for few sec on start and how to solve this issue ?
You can use the package flutter_native_splash to add native splash screens for Android and iOS without the manual changes described in other answers.
The package does the manual changes for you.
1 - Depend on it:
dev_dependencies:
flutter_native_splash: ^0.1.4
And flutter pub get
2 - Configure your splash screen on pubspec.yaml:
flutter_native_splash:
image: assets/images/splash.png
color: 42a5f5
3 - Run the package
flutter pub pub run flutter_native_splash:create
Splash screens are now generated.