login.js

import React, { PureComponent } from 'react'
import { View, Text, Button, AsyncStorage } from 'react-native'
import { connect } from 'react-redux'

class LoginScreen extends PureComponent {
  constructor (props) {
    super(props)
    this.attemptLogin = this.attemptLogin.bind(this)
  }

  attemptLogin () {
    // Send request to server and validate login here

    var token = 'somerandomtoken'
    return token
  }

  render () {
    return (
      <View style={{ flex: 1, backgroundColor: '#ffffff', alignItems: 'center', justifyContent: 'center' }}>
        <Text children='Redux Login Example' />
        <Text children='Click on login to continue' />
        <Button color='#90100' title='Login' onPress={this.attemptLogin} />
      </View>
    )
  }
}

const mapStateToProps = (state, ownProps) => {
  return {}
}

export const actionCreator = (action, payload = null) => ({ action, payload })

const mapDispatchToProps = (dispatch, ownProps) => {
  return {
    authSuccess: (token) => {
      AsyncStorage.multiSet([['token', token], ['authenticated', 1]])
      dispatch(actionCreator('LOGIN_SUCCESS'))
    }
  }
}

export const authStateReducer = (state = { authenticated: false, appStarted: false }, { type, payload }) => {
  switch (type) {
    case 'LOGIN_SUCCESS':
      return { ...state, authenticated: true }
    case 'LOGGOUT':
      return { ...state, authenticated: false }
    case 'APP_LOADED':
      return { ...state, appStarted: true }
    default:
      return state
  }
}
export default connect(mapStateToProps, mapDispatchToProps)(LoginScreen)