Sagas to write localstorage and read it back. Gotta save info in state instead...

Preferences.sagas.js

import { call, put, takeLatest, take, race } from 'redux-saga/effects'
import {
  SWITCH_BIOMETRIC_UNLOCK_REQUEST,
  SWITCH_BIOMETRIC_UNLOCK_REJECTED,
  SWITCH_BIOMETRIC_UNLOCK_SUCCESS,
} from './Preferences.actions'
import {
  CLOSE_PASSWORD_MODAL,
  OPEN_PASSWORD_MODAL,
  PASSWORD_VALIDATED,
} from 'app/redux/PasswordPromptModal.actions'
import FingerprintService from 'app/native/FingerprintService'

export default () => [
  takeLatest(SWITCH_BIOMETRIC_UNLOCK_REQUEST, onSwitchBiometricUnlock),
]

function* onSwitchBiometricUnlock({ payload: { enable } }) {
  if (enable) {
    yield call(activateBiometricUnlock)
    return
  }
  yield call(disableBiometricUnlock)
}

function* activateBiometricUnlock() {
  const isAvailable = yield call(FingerprintService.isAvailable)

  if (!isAvailable) {
    yield put(uiActions.pushPage({ component: pages.TurnOnFingerprintInfo, }))
    yield put(SWITCH_BIOMETRIC_UNLOCK_REJECTED())
    return
  }

  yield put(OPEN_PASSWORD_MODAL())

  const {
    cancel,
    validPassword: {
      payload: { password },
    },
  } = yield race({
    validPassword: take(PASSWORD_VALIDATED),
    cancel: take(CLOSE_PASSWORD_MODAL),
  })

  if (cancel) {
    yield put(SWITCH_BIOMETRIC_UNLOCK_REJECTED())
    return
  }

  try {
    const token = yield call(FingerprintService.encrypt, password)
    yield call(defaultStorage.setItem, 'fingerprintEncryptedPassword', token)
    yield put(SWITCH_BIOMETRIC_UNLOCK_SUCCESS(true))
  } catch (e) {
    console.log(`It is not possible to activate the Fingerprint ${e.toString()}`)
  }
}

function* disableBiometricUnlock() {
  yield call(FingerprintService.delete)
  yield call(defaultStorage.removeItem, 'fingerprintEncryptedPassword')
  yield put(SWITCH_BIOMETRIC_UNLOCK_SUCCESS(false))
}

ui.sagas.js

import { takeLatest, call, put, select, takeEvery } from 'redux-saga/effects'
import actions from './ui.actions'
import splashScreen from 'app/native/splashScreen'
import {SWITCH_BIOMETRIC_UNLOCK_SUCCESS} from 'app/ui/pages/Preferences/redux/Preferences.actions'

function* bootUi(action) {

  try {
    yield splashScreen.show()
    
    const isFingerprintEnabled = yield call(storage.getItem, 'fingerprintEncryptedPassword')
    yield put(SWITCH_BIOMETRIC_UNLOCK_SUCCESS(typeof isFingerprintEnabled !== 'undefined'))

  } catch (e) {
    yield put(actions.genericError())
  } finally {
    splashScreen.hide()
  }
}