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<html><head><meta charset="utf-8"/><meta http-equiv="X-UA-Compatible" content="IE=edge, chrome=1"/><title>AppState · React Native</title><meta name="viewport" content="width=device-width"/><meta name="generator" content="Docusaurus"/><meta property="og:title" content="AppState · React Native"/><meta property="og:type" content="website"/><meta property="og:url" content="https://facebook.github.io/react-native/index.html"/><meta property="og:description" content="`AppState` can tell you if the app is in the foreground or background, and notify you when the state changes."/><link rel="shortcut icon" href="/react-native/img/favicon.png"/><link rel="stylesheet" href="https://cdn.jsdelivr.net/docsearch.js/1/docsearch.min.css"/><link rel="stylesheet" href="//cdnjs.cloudflare.com/ajax/libs/highlight.js/9.12.0/styles/solarized-dark.min.css"/><link rel="alternate" type="application/atom+xml" href="https://facebook.github.io/blog/atom.xml" title="React Native Blog ATOM Feed"/><link rel="alternate" type="application/rss+xml" href="https://facebook.github.io/blog/feed.xml" title="React Native Blog RSS Feed"/><script type="text/javascript" src="https://snack.expo.io/embed.js"></script><script type="text/javascript" src="/react-native/js/codeblocks.js"></script><link rel="stylesheet" href="/react-native/css/main.css"/></head><body class="sideNavVisible"><div class="fixedHeaderContainer"><div class="headerWrapper wrapper"><header><a href="/react-native/"><img class="logo" src="/react-native/img/header_logo.png"/><h2 class="headerTitle">React Native</h2></a><a href="/react-native/versions.html"><h3>0.13</h3></a><div class="navigationWrapper navigationSlider"><nav class="slidingNav"><ul class="nav-site nav-site-internal"><li><a href="/react-native/docs/0.13/getting-started.html" target="_self">Docs</a></li><li><a href="/react-native/en/help.html" target="_self">Community</a></li><li><a href="/react-native/blog" target="_self">Blog</a></li><li class="navSearchWrapper reactNavSearchWrapper"><input type="text" id="search_input_react" placeholder="Search"/></li><li><a href="https://github.com/facebook/react-native" target="_self">GitHub</a></li><li><a href="https://reactjs.org/" target="_self">React</a></li></ul></nav></div></header></div></div><div class="navPusher"><div class="docMainWrapper wrapper"><div class="container mainContainer"><div class="wrapper"><div class="post"><header class="postHeader"><a class="edit-page-link button" href="https://github.com/facebook/react-native-website/blob/master/docs/appstate.md" target="_blank">Edit</a><h1>AppState</h1></header><article><div><span><p><code>AppState</code> can tell you if the app is in the foreground or background, and notify you when the state changes.</p>
<p>App state is frequently used to determine the intent and proper behavior when handling push notifications.</p>
<h3><a class="anchor" aria-hidden="true" name="app-states"></a><a href="#app-states" aria-hidden="true" class="hash-link" ><svg aria-hidden="true" height="16" version="1.1" viewBox="0 0 16 16" width="16"><path fill-rule="evenodd" d="M4 9h1v1H4c-1.5 0-3-1.69-3-3.5S2.55 3 4 3h4c1.45 0 3 1.69 3 3.5 0 1.41-.91 2.72-2 3.25V8.59c.58-.45 1-1.27 1-2.09C10 5.22 8.98 4 8 4H4c-.98 0-2 1.22-2 2.5S3 9 4 9zm9-3h-1v1h1c1 0 2 1.22 2 2.5S13.98 12 13 12H9c-.98 0-2-1.22-2-2.5 0-.83.42-1.64 1-2.09V6.25c-1.09.53-2 1.84-2 3.25C6 11.31 7.55 13 9 13h4c1.45 0 3-1.69 3-3.5S14.5 6 13 6z"></path></svg></a>App States</h3>
<ul>
<li><code>active</code> - The app is running in the foreground</li>
<li><code>background</code> - The app is running in the background. The user is either in another app or on the home screen</li>
<li><code>inactive</code> - This is a state that occurs when transitioning between foreground &amp; background, and during periods of inactivity such as entering the Multitasking view or in the event of an incoming call</li>
</ul>
<p>For more information, see <a href="https://developer.apple.com/library/ios/documentation/iPhone/Conceptual/iPhoneOSProgrammingGuide/TheAppLifeCycle/TheAppLifeCycle.html">Apple's documentation</a>.</p>
<h3><a class="anchor" aria-hidden="true" name="basic-usage"></a><a href="#basic-usage" aria-hidden="true" class="hash-link" ><svg aria-hidden="true" height="16" version="1.1" viewBox="0 0 16 16" width="16"><path fill-rule="evenodd" d="M4 9h1v1H4c-1.5 0-3-1.69-3-3.5S2.55 3 4 3h4c1.45 0 3 1.69 3 3.5 0 1.41-.91 2.72-2 3.25V8.59c.58-.45 1-1.27 1-2.09C10 5.22 8.98 4 8 4H4c-.98 0-2 1.22-2 2.5S3 9 4 9zm9-3h-1v1h1c1 0 2 1.22 2 2.5S13.98 12 13 12H9c-.98 0-2-1.22-2-2.5 0-.83.42-1.64 1-2.09V6.25c-1.09.53-2 1.84-2 3.25C6 11.31 7.55 13 9 13h4c1.45 0 3-1.69 3-3.5S14.5 6 13 6z"></path></svg></a>Basic Usage</h3>
<p>To see the current state, you can check <code>AppState.currentState</code>, which will be kept up-to-date. However, <code>currentState</code> will be null at launch while <code>AppState</code> retrieves it over the bridge.</p>
<pre><code class="hljs css javascript"><span class="hljs-keyword">import</span> React, {Component} <span class="hljs-keyword">from</span> <span class="hljs-string">'react'</span>;
<span class="hljs-keyword">import</span> {AppState, Text} <span class="hljs-keyword">from</span> <span class="hljs-string">'react-native'</span>;
<span class="hljs-class"><span class="hljs-keyword">class</span> <span class="hljs-title">AppStateExample</span> <span class="hljs-keyword">extends</span> <span class="hljs-title">Component</span> </span>{
state = {
<span class="hljs-attr">appState</span>: AppState.currentState,
};
componentDidMount() {
AppState.addEventListener(<span class="hljs-string">'change'</span>, <span class="hljs-keyword">this</span>._handleAppStateChange);
}
componentWillUnmount() {
AppState.removeEventListener(<span class="hljs-string">'change'</span>, <span class="hljs-keyword">this</span>._handleAppStateChange);
}
_handleAppStateChange = <span class="hljs-function">(<span class="hljs-params">nextAppState</span>) =&gt;</span> {
<span class="hljs-keyword">if</span> (
<span class="hljs-keyword">this</span>.state.appState.match(<span class="hljs-regexp">/inactive|background/</span>) &amp;&amp;
nextAppState === <span class="hljs-string">'active'</span>
) {
<span class="hljs-built_in">console</span>.log(<span class="hljs-string">'App has come to the foreground!'</span>);
}
<span class="hljs-keyword">this</span>.setState({<span class="hljs-attr">appState</span>: nextAppState});
};
render() {
<span class="hljs-keyword">return</span> <span class="xml"><span class="hljs-tag">&lt;<span class="hljs-name">Text</span>&gt;</span>Current state is: {this.state.appState}<span class="hljs-tag">&lt;/<span class="hljs-name">Text</span>&gt;</span></span>;
}
}
</code></pre>
<p>This example will only ever appear to say &quot;Current state is: active&quot; because the app is only visible to the user when in the <code>active</code> state, and the null state will happen only momentarily.</p>
<h3><a class="anchor" aria-hidden="true" name="methods"></a><a href="#methods" aria-hidden="true" class="hash-link" ><svg aria-hidden="true" height="16" version="1.1" viewBox="0 0 16 16" width="16"><path fill-rule="evenodd" d="M4 9h1v1H4c-1.5 0-3-1.69-3-3.5S2.55 3 4 3h4c1.45 0 3 1.69 3 3.5 0 1.41-.91 2.72-2 3.25V8.59c.58-.45 1-1.27 1-2.09C10 5.22 8.98 4 8 4H4c-.98 0-2 1.22-2 2.5S3 9 4 9zm9-3h-1v1h1c1 0 2 1.22 2 2.5S13.98 12 13 12H9c-.98 0-2-1.22-2-2.5 0-.83.42-1.64 1-2.09V6.25c-1.09.53-2 1.84-2 3.25C6 11.31 7.55 13 9 13h4c1.45 0 3-1.69 3-3.5S14.5 6 13 6z"></path></svg></a>Methods</h3>
<ul>
<li><a href="/react-native/docs/0.13/appstate.html#addeventlistener"><code>addEventListener</code></a></li>
<li><a href="/react-native/docs/0.13/appstate.html#removeeventlistener"><code>removeEventListener</code></a></li>
</ul>
<hr>
<h1><a class="anchor" aria-hidden="true" name="reference"></a><a href="#reference" aria-hidden="true" class="hash-link" ><svg aria-hidden="true" height="16" version="1.1" viewBox="0 0 16 16" width="16"><path fill-rule="evenodd" d="M4 9h1v1H4c-1.5 0-3-1.69-3-3.5S2.55 3 4 3h4c1.45 0 3 1.69 3 3.5 0 1.41-.91 2.72-2 3.25V8.59c.58-.45 1-1.27 1-2.09C10 5.22 8.98 4 8 4H4c-.98 0-2 1.22-2 2.5S3 9 4 9zm9-3h-1v1h1c1 0 2 1.22 2 2.5S13.98 12 13 12H9c-.98 0-2-1.22-2-2.5 0-.83.42-1.64 1-2.09V6.25c-1.09.53-2 1.84-2 3.25C6 11.31 7.55 13 9 13h4c1.45 0 3-1.69 3-3.5S14.5 6 13 6z"></path></svg></a>Reference</h1>
<h2><a class="anchor" aria-hidden="true" name="methods"></a><a href="#methods" aria-hidden="true" class="hash-link" ><svg aria-hidden="true" height="16" version="1.1" viewBox="0 0 16 16" width="16"><path fill-rule="evenodd" d="M4 9h1v1H4c-1.5 0-3-1.69-3-3.5S2.55 3 4 3h4c1.45 0 3 1.69 3 3.5 0 1.41-.91 2.72-2 3.25V8.59c.58-.45 1-1.27 1-2.09C10 5.22 8.98 4 8 4H4c-.98 0-2 1.22-2 2.5S3 9 4 9zm9-3h-1v1h1c1 0 2 1.22 2 2.5S13.98 12 13 12H9c-.98 0-2-1.22-2-2.5 0-.83.42-1.64 1-2.09V6.25c-1.09.53-2 1.84-2 3.25C6 11.31 7.55 13 9 13h4c1.45 0 3-1.69 3-3.5S14.5 6 13 6z"></path></svg></a>Methods</h2>
<h3><a class="anchor" aria-hidden="true" name="addeventlistener"></a><a href="#addeventlistener" aria-hidden="true" class="hash-link" ><svg aria-hidden="true" height="16" version="1.1" viewBox="0 0 16 16" width="16"><path fill-rule="evenodd" d="M4 9h1v1H4c-1.5 0-3-1.69-3-3.5S2.55 3 4 3h4c1.45 0 3 1.69 3 3.5 0 1.41-.91 2.72-2 3.25V8.59c.58-.45 1-1.27 1-2.09C10 5.22 8.98 4 8 4H4c-.98 0-2 1.22-2 2.5S3 9 4 9zm9-3h-1v1h1c1 0 2 1.22 2 2.5S13.98 12 13 12H9c-.98 0-2-1.22-2-2.5 0-.83.42-1.64 1-2.09V6.25c-1.09.53-2 1.84-2 3.25C6 11.31 7.55 13 9 13h4c1.45 0 3-1.69 3-3.5S14.5 6 13 6z"></path></svg></a><code>addEventListener()</code></h3>
<pre><code class="hljs css javascript">addEventListener(type, handler);
</code></pre>
<p>Add a handler to AppState changes by listening to the <code>change</code> event type and providing the handler.</p>
<p><strong>Parameters:</strong></p>
<table>
<thead>
<tr><th>Name</th><th>Type</th><th>Required</th><th>Description</th></tr>
</thead>
<tbody>
<tr><td>type</td><td>string</td><td>Yes</td><td></td></tr>
<tr><td>handler</td><td>function</td><td>Yes</td><td></td></tr>
</tbody>
</table>
<hr>
<h3><a class="anchor" aria-hidden="true" name="removeeventlistener"></a><a href="#removeeventlistener" aria-hidden="true" class="hash-link" ><svg aria-hidden="true" height="16" version="1.1" viewBox="0 0 16 16" width="16"><path fill-rule="evenodd" d="M4 9h1v1H4c-1.5 0-3-1.69-3-3.5S2.55 3 4 3h4c1.45 0 3 1.69 3 3.5 0 1.41-.91 2.72-2 3.25V8.59c.58-.45 1-1.27 1-2.09C10 5.22 8.98 4 8 4H4c-.98 0-2 1.22-2 2.5S3 9 4 9zm9-3h-1v1h1c1 0 2 1.22 2 2.5S13.98 12 13 12H9c-.98 0-2-1.22-2-2.5 0-.83.42-1.64 1-2.09V6.25c-1.09.53-2 1.84-2 3.25C6 11.31 7.55 13 9 13h4c1.45 0 3-1.69 3-3.5S14.5 6 13 6z"></path></svg></a><code>removeEventListener()</code></h3>
<pre><code class="hljs css javascript">removeEventListener(type, handler);
</code></pre>
<p>Remove a handler by passing the <code>change</code> event type and the handler.</p>
<p><strong>Parameters:</strong></p>
<table>
<thead>
<tr><th>Name</th><th>Type</th><th>Required</th><th>Description</th></tr>
</thead>
<tbody>
<tr><td>type</td><td>string</td><td>Yes</td><td></td></tr>
<tr><td>handler</td><td>function</td><td>Yes</td><td></td></tr>
</tbody>
</table>
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