Closing React Native Android App with Back Button (Using react-native-router-flux)

App.js

import { BackHandler } from 'react-native'
import { Actions, Router } from 'react-native-router-flux'

class App extends Component {
  componentDidMount () {
    this.backHandler = BackHandler.addEventListener('hardwareBackPress', this.handleBackPress)
  }

  componentWillUnmount() {
    this.backHandler.remove()
  }

  handleBackPress = () => {
    switch (Actions.currentScene) {
      case 'home':
        BackHandler.exitApp()
        break

      default: Actions.pop()
    }

    return true
  }
  
// Define scenes for routing
const scenes = Actions.create(
  <Scene key='root' navTransparent>
    <Scene
      initial={true}
      key='home'
      component={Home}
      type='replace'
      hideNavBar
    />
    
    ...

    <Scene
      key='signUp'
      component={SignUp}
      type='push'
      renderBackButton={getBackButton}
    />

    <Scene
      key='signIn'
      component={SignIn}
      type='push'
      renderBackButton={getBackButton}
    />
  </Scene>
)

  render () {
    return <Router scenes={scenes} />
  }
}