flutter-brownfield - android - MainActivity.kt

package com.example.flutter_brownfield_app

import android.content.Intent
import android.view.KeyEvent
import com.facebook.react.ReactInstanceManager
import com.facebook.react.ReactNativeHost
import com.facebook.react.modules.core.DefaultHardwareBackBtnHandler
import io.flutter.embedding.android.FlutterActivity
// ...

class MainActivity: FlutterActivity(), DefaultHardwareBackBtnHandler {
    // ...

    // Easy access to ReactNativeHost
    private val reactNativeHost: ReactNativeHost
        get() = (application as MainApplication).reactNativeHost
        
    // Easy access to ReactNativeHost
    private val reactInstanceManager: ReactInstanceManager
        get() = (application as MainApplication).reactNativeHost.reactInstanceManager

    // ...

    // Inform React Native Host about "onPause" lifecycle event
    override fun onPause() {
        super.onPause()
        reactInstanceManager.onHostPause(this)
    }

    // Inform React Native Host about "onResume" lifecycle event
    override fun onResume() {
        super.onResume()
        reactInstanceManager.onHostResume(this, this)
    }

    // Inform React Native Host about "onDestroy" lifecycle event
    override fun onDestroy() {
        super.onDestroy()
        reactInstanceManager.onHostDestroy(this)
    }

    // Inform React Native Host about "onBackPressed" lifecycle event
    override fun onBackPressed() {
        reactInstanceManager.onBackPressed()
        super.onBackPressed()
    }

    // Trigger Dev Options dialog when user presses "menu" button on Simulator.
    override fun onKeyUp(keyCode: Int, event: KeyEvent): Boolean {
        if (keyCode == KeyEvent.KEYCODE_MENU && reactNativeHost.hasInstance()) {
            reactInstanceManager.showDevOptionsDialog()
            return true
        }
        return super.onKeyUp(keyCode, event)
    }

    // Required by DefaultHardwareBackBtnHandler
    override fun invokeDefaultOnBackPressed() {
        super.onBackPressed()
    }
}