AppStateAndroid.js

/**
 * Copyright 2004-present Facebook. All Rights Reserved.
 *
 * @providesModule AppStateAndroid
 */
'use strict';

var Map = require('Map');
var RCTDeviceEventEmitter = require('RCTDeviceEventEmitter');
var AppState = require('NativeModules').AppStateAndroid;

var logError = require('logError');

var APP_LIFECYCLE_EVENT = 'appLifecycleEvent';

var _appStateHandlers = new Map();

/**
 * This class can be used to register to host lifecycle events (ie. paused, resumed).
 * Alternatively, one can query AppStateAndroid.currentState to get the current host state.
 */
class AppStateAndroid {

  static addEventListener(handler) {
    var listener = RCTDeviceEventEmitter.addListener(
      APP_LIFECYCLE_EVENT,
      (hostLifecycleEventData) => {
        handler(hostLifecycleEventData);
      }
    );
    _appStateHandlers.set(handler, listener);
  }

  static removeEventListener(handler) {
    var listener = _appStateHandlers.get(handler);
    if (!listener) {
      return;
    }
    listener.remove();
    _appStateHandlers.delete(handler);
  }
}

AppStateAndroid.currentState = null;

RCTDeviceEventEmitter.addListener(
  APP_LIFECYCLE_EVENT,
  (hostLifecycleEventData) => {
    AppStateAndroid.currentState = hostLifecycleEventData;
  }
);

AppState.getCurrentAppState(
  (hostLifecycleEventData) => {
    AppStateAndroid.currentState = hostLifecycleEventData;
  },
  logError
);

module.exports = AppStateAndroid;