143 lines
3.9 KiB
JavaScript
143 lines
3.9 KiB
JavaScript
/**
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* Copyright (c) 2015-present, Facebook, Inc.
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* All rights reserved.
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*
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* This source code is licensed under the BSD-style license found in the
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* LICENSE file in the root directory of this source tree. An additional grant
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* of patent rights can be found in the PATENTS file in the same directory.
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*
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* @providesModule AppState
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* @flow
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*/
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'use strict';
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var Map = require('Map');
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var NativeModules = require('NativeModules');
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var RCTDeviceEventEmitter = require('RCTDeviceEventEmitter');
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var RCTAppState = NativeModules.AppState;
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var logError = require('logError');
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var invariant = require('fbjs/lib/invariant');
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var _eventHandlers = {
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change: new Map(),
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memoryWarning: new Map(),
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};
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/**
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* `AppState` can tell you if the app is in the foreground or background,
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* and notify you when the state changes.
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*
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* AppState is frequently used to determine the intent and proper behavior when
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* handling push notifications.
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*
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* ### App States
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*
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* - `active` - The app is running in the foreground
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* - `background` - The app is running in the background. The user is either
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* in another app or on the home screen
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* - `inactive` - This is a transition state that currently never happens for
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* typical React Native apps.
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*
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* For more information, see
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* [Apple's documentation](https://developer.apple.com/library/ios/documentation/iPhone/Conceptual/iPhoneOSProgrammingGuide/TheAppLifeCycle/TheAppLifeCycle.html)
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*
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* ### Basic Usage
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*
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* To see the current state, you can check `AppState.currentState`, which
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* will be kept up-to-date. However, `currentState` will be null at launch
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* while `AppState` retrieves it over the bridge.
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*
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* ```
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* getInitialState: function() {
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* return {
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* currentAppState: AppState.currentState,
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* };
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* },
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* componentDidMount: function() {
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* AppState.addEventListener('change', this._handleAppStateChange);
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* },
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* componentWillUnmount: function() {
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* AppState.removeEventListener('change', this._handleAppStateChange);
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* },
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* _handleAppStateChange: function(currentAppState) {
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* this.setState({ currentAppState, });
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* },
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* render: function() {
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* return (
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* <Text>Current state is: {this.state.currentAppState}</Text>
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* );
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* },
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* ```
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*
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* This example will only ever appear to say "Current state is: active" because
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* the app is only visible to the user when in the `active` state, and the null
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* state will happen only momentarily.
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*/
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var AppState = {
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/**
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* Add a handler to AppState changes by listening to the `change` event type
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* and providing the handler
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*/
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addEventListener: function(
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type: string,
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handler: Function
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) {
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invariant(
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['change', 'memoryWarning'].indexOf(type) !== -1,
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'Trying to subscribe to unknown event: "%s"', type
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);
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if (type === 'change') {
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_eventHandlers[type].set(handler, RCTDeviceEventEmitter.addListener(
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'appStateDidChange',
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(appStateData) => {
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handler(appStateData.app_state);
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}
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));
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} else if (type === 'memoryWarning') {
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_eventHandlers[type].set(handler, RCTDeviceEventEmitter.addListener(
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'memoryWarning',
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handler
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));
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}
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},
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/**
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* Remove a handler by passing the `change` event type and the handler
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*/
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removeEventListener: function(
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type: string,
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handler: Function
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) {
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invariant(
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['change', 'memoryWarning'].indexOf(type) !== -1,
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'Trying to remove listener for unknown event: "%s"', type
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);
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if (!_eventHandlers[type].has(handler)) {
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return;
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}
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_eventHandlers[type].get(handler).remove();
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_eventHandlers[type].delete(handler);
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},
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currentState: ('active' : ?string),
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};
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RCTDeviceEventEmitter.addListener(
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'appStateDidChange',
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(appStateData) => {
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AppState.currentState = appStateData.app_state;
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}
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);
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RCTAppState.getCurrentAppState(
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(appStateData) => {
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AppState.currentState = appStateData.app_state;
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},
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logError
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);
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module.exports = AppState;
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