flutter-sample-custom-platform-specific-code

Flutter Writing custom platform-specific code
https://flutter.dev/docs/development/platform-integration/platform-channels

The following sample demonstrates how to call a platform-specific API to retrieve and display the current battery level.

Android

Android platform-specific implementation using Java

iOS

iOS platform-specific implementation using Objective-C

for Kotlin, Swift Sample

https://github.com/unsolublesugar/flutter-sample-custom-platform-specific-code