react-native/Libraries/AppStateIOS/AppStateIOS.ios.js

126 lines
3.4 KiB
JavaScript

/**
* Copyright (c) 2015-present, Facebook, Inc.
* All rights reserved.
*
* This source code is licensed under the BSD-style license found in the
* LICENSE file in the root directory of this source tree. An additional grant
* of patent rights can be found in the PATENTS file in the same directory.
*
* @providesModule AppStateIOS
* @flow
*/
'use strict';
var NativeModules = require('NativeModules');
var RCTDeviceEventEmitter = require('RCTDeviceEventEmitter');
var RCTAppState = NativeModules.AppState;
var logError = require('logError');
var DEVICE_APPSTATE_EVENT = 'appStateDidChange';
var _appStateHandlers = {};
/**
* `AppStateIOS` can tell you if the app is in the foreground or background,
* and notify you when the state changes.
*
* AppStateIOS is frequently used to determine the intent and proper behavior when
* handling push notifications.
*
* ### iOS App States
*
* - `active` - The app is running in the foreground
* - `background` - The app is running in the background. The user is either
* in another app or on the home screen
* - `inactive` - This is a transition state that currently never happens for
* typical React Native apps.
*
* For more information, see
* [Apple's documentation](https://developer.apple.com/library/ios/documentation/iPhone/Conceptual/iPhoneOSProgrammingGuide/TheAppLifeCycle/TheAppLifeCycle.html)
*
* ### Basic Usage
*
* To see the current state, you can check `AppStateIOS.currentState`, which
* will be kept up-to-date. However, `currentState` will be null at launch
* while `AppStateIOS` retrieves it over the bridge.
*
* ```
* getInitialState: function() {
* return {
* currentAppState: AppStateIOS.currentState,
* };
* },
* componentDidMount: function() {
* AppStateIOS.addEventListener('change', this._handleAppStateChange);
* },
* componentWillUnmount: function() {
* AppStateIOS.removeEventListener('change', this._handleAppStateChange);
* },
* _handleAppStateChange: function(currentAppState) {
* this.setState({ currentAppState, });
* },
* render: function() {
* return (
* <Text>Current state is: {this.state.currentAppState}</Text>
* );
* },
* ```
*
* This example will only ever appear to say "Current state is: active" because
* the app is only visible to the user when in the `active` state, and the null
* state will happen only momentarily.
*/
var AppStateIOS = {
/**
* Add a handler to AppState changes by listening to the `change` event type
* and providing the handler
*/
addEventListener: function(
type: string,
handler: Function
) {
_appStateHandlers[handler] = RCTDeviceEventEmitter.addListener(
DEVICE_APPSTATE_EVENT,
(appStateData) => {
handler(appStateData.app_state);
}
);
},
/**
* Remove a handler by passing the `change` event type and the handler
*/
removeEventListener: function(
type: string,
handler: Function
) {
if (!_appStateHandlers[handler]) {
return;
}
_appStateHandlers[handler].remove();
_appStateHandlers[handler] = null;
},
currentState: (null : ?String),
};
RCTDeviceEventEmitter.addListener(
DEVICE_APPSTATE_EVENT,
(appStateData) => {
AppStateIOS.currentState = appStateData.app_state;
}
);
RCTAppState.getCurrentAppState(
(appStateData) => {
AppStateIOS.currentState = appStateData.app_state;
},
logError
);
module.exports = AppStateIOS;