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<!DOCTYPE html><html lang="en"><head><meta charSet="utf-8"/><meta http-equiv="X-UA-Compatible" content="IE=edge"/><title>AppState · React Native</title><meta name="viewport" content="width=device-width"/><meta name="generator" content="Docusaurus"/><meta name="description" content="`AppState` can tell you if the app is in the foreground or background, and notify you when the state changes."/><meta name="docsearch:version" content="0.62"/><meta name="docsearch:language" content="en"/><meta property="og:title" content="AppState · React Native"/><meta property="og:type" content="website"/><meta property="og:url" content="https://reactnative.dev/"/><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."/><meta property="og:image" content="https://reactnative.dev/img/logo-og.png"/><meta name="twitter:card" content="summary"/><meta name="twitter:image" content="https://reactnative.dev/img/logo-og.png"/><link rel="shortcut icon" href="/img/favicon.ico"/><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://reactnative.dev/blog/atom.xml" title="React Native Blog ATOM Feed"/><link rel="alternate" type="application/rss+xml" href="https://reactnative.dev/blog/feed.xml" title="React Native Blog RSS Feed"/><script>
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</script></nav></div><div class="container mainContainer docsContainer"><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" rel="noreferrer noopener">Edit</a><h1 id="__docusaurus" class="postHeaderTitle">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>
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<p>AppState is frequently used to determine the intent and proper behavior when handling push notifications.</p>
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<h3><a class="anchor" aria-hidden="true" id="app-states"></a><a href="#app-states" aria-hidden="true" class="hash-link"><svg class="hash-link-icon" 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>
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<ul>
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<li><code>active</code> - The app is running in the foreground</li>
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<li><code>background</code> - The app is running in the background. The user is either:
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<ul>
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<li>in another app</li>
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<li>on the home screen</li>
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<li>[Android] on another <code>Activity</code> (even if it was launched by your app)</li>
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</ul></li>
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<li>[iOS] <code>inactive</code> - This is a state that occurs when transitioning between foreground & background, and during periods of inactivity such as entering the Multitasking view or in the event of an incoming call</li>
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</ul>
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<p>For more information, see <a href="https://developer.apple.com/documentation/uikit/app_and_scenes/managing_your_app_s_life_cycle">Apple's documentation</a></p>
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<h2><a class="anchor" aria-hidden="true" id="basic-usage"></a><a href="#basic-usage" aria-hidden="true" class="hash-link"><svg class="hash-link-icon" 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</h2>
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<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>
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<div class="toggler">
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<ul role="tablist" class="toggle-syntax">
|
||
<li id="functional" class="button-functional" aria-selected="false" role="tab" tabindex="0" aria-controls="functionaltab" onclick="displayTabs('syntax', 'functional')">
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||
Function Component Example
|
||
</li>
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||
<li id="classical" class="button-classical" aria-selected="false" role="tab" tabindex="0" aria-controls="classicaltab" onclick="displayTabs('syntax', 'classical')">
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||
Class Component Example
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||
</li>
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||
</ul>
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</div>
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<p><block class="functional syntax" /></p>
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||
<div class="snack-player"><div class="mobile-friendly-snack" style="display: none"><pre><code class="hljs css javascript"><span class="hljs-keyword">import</span> React, { useEffect, useState } <span class="hljs-keyword">from</span> <span class="hljs-string">"react"</span>;
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<span class="hljs-keyword">import</span> { AppState, StyleSheet, Text, View } <span class="hljs-keyword">from</span> <span class="hljs-string">"react-native"</span>;
|
||
|
||
<span class="hljs-keyword">const</span> AppStateExample = <span class="hljs-function"><span class="hljs-params">()</span> =></span> {
|
||
<span class="hljs-keyword">const</span> [appState, setAppState] = useState(AppState.currentState);
|
||
|
||
useEffect(<span class="hljs-function"><span class="hljs-params">()</span> =></span> {
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||
AppState.addEventListener(<span class="hljs-string">"change"</span>, _handleAppStateChange);
|
||
|
||
<span class="hljs-keyword">return</span> <span class="hljs-function"><span class="hljs-params">()</span> =></span> {
|
||
AppState.removeEventListener(<span class="hljs-string">"change"</span>, _handleAppStateChange);
|
||
};
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||
}, []);
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||
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||
<span class="hljs-keyword">const</span> _handleAppStateChange = <span class="hljs-function"><span class="hljs-params">nextAppState</span> =></span> {
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||
<span class="hljs-keyword">if</span> (appState.match(<span class="hljs-regexp">/inactive|background/</span>) && nextAppState === <span class="hljs-string">"active"</span>) {
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<span class="hljs-built_in">console</span>.log(<span class="hljs-string">"App has come to the foreground!"</span>);
|
||
}
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||
setAppState(nextAppState);
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||
};
|
||
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||
<span class="hljs-keyword">return</span> (
|
||
<span class="xml"><span class="hljs-tag"><<span class="hljs-name">View</span> <span class="hljs-attr">style</span>=<span class="hljs-string">{styles.container}</span>></span>
|
||
<span class="hljs-tag"><<span class="hljs-name">Text</span>></span>Current state is: {appState}<span class="hljs-tag"></<span class="hljs-name">Text</span>></span>
|
||
<span class="hljs-tag"></<span class="hljs-name">View</span>></span></span>
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||
);
|
||
};
|
||
|
||
<span class="hljs-keyword">const</span> styles = StyleSheet.create({
|
||
<span class="hljs-attr">container</span>: {
|
||
<span class="hljs-attr">flex</span>: <span class="hljs-number">1</span>,
|
||
<span class="hljs-attr">justifyContent</span>: <span class="hljs-string">"center"</span>,
|
||
<span class="hljs-attr">alignItems</span>: <span class="hljs-string">"center"</span>
|
||
}
|
||
});
|
||
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||
<span class="hljs-keyword">export</span> <span class="hljs-keyword">default</span> AppStateExample;
|
||
</code></pre></div><div class="desktop-friendly-snack" style="margin-top: 15px; margin-bottom: 15px"><div
|
||
data-snack-name="AppState Function Component Example"
|
||
data-snack-description="Example usage"
|
||
data-snack-code="import%20React%2C%20%7B%20useEffect%2C%20useState%20%7D%20from%20%22react%22%3B%0Aimport%20%7B%20AppState%2C%20StyleSheet%2C%20Text%2C%20View%20%7D%20from%20%22react-native%22%3B%0A%0Aconst%20AppStateExample%20%3D%20()%20%3D%3E%20%7B%0A%20%20const%20%5BappState%2C%20setAppState%5D%20%3D%20useState(AppState.currentState)%3B%0A%0A%20%20useEffect(()%20%3D%3E%20%7B%0A%20%20%20%20AppState.addEventListener(%22change%22%2C%20_handleAppStateChange)%3B%0A%0A%20%20%20%20return%20()%20%3D%3E%20%7B%0A%20%20%20%20%20%20AppState.removeEventListener(%22change%22%2C%20_handleAppStateChange)%3B%0A%20%20%20%20%7D%3B%0A%20%20%7D%2C%20%5B%5D)%3B%0A%0A%20%20const%20_handleAppStateChange%20%3D%20nextAppState%20%3D%3E%20%7B%0A%20%20%20%20if%20(appState.match(%2Finactive%7Cbackground%2F)%20%26%26%20nextAppState%20%3D%3D%3D%20%22active%22)%20%7B%0A%20%20%20%20%20%20console.log(%22App%20has%20come%20to%20the%20foreground!%22)%3B%0A%20%20%20%20%7D%0A%20%20%20%20setAppState(nextAppState)%3B%0A%20%20%7D%3B%0A%0A%20%20return%20(%0A%20%20%20%20%3CView%20style%3D%7Bstyles.container%7D%3E%0A%20%20%20%20%20%20%3CText%3ECurrent%20state%20is%3A%20%7BappState%7D%3C%2FText%3E%0A%20%20%20%20%3C%2FView%3E%0A%20%20)%3B%0A%7D%3B%0A%0Aconst%20styles%20%3D%20StyleSheet.create(%7B%0A%20%20container%3A%20%7B%0A%20%20%20%20flex%3A%201%2C%0A%20%20%20%20justifyContent%3A%20%22center%22%2C%0A%20%20%20%20alignItems%3A%20%22center%22%0A%20%20%7D%0A%7D)%3B%0A%0Aexport%20default%20AppStateExample%3B%0A"
|
||
data-snack-platform="web"
|
||
data-snack-supported-platforms=ios,android,web
|
||
data-snack-preview="true"
|
||
style="
|
||
overflow: hidden;
|
||
background: #fafafa;
|
||
border: 1px solid rgba(0,0,0,.16);
|
||
border-radius: 4px;
|
||
height: 514px;
|
||
width: 100%;
|
||
"
|
||
></div></div></div><p><block class="classical syntax" /></p>
|
||
<div class="snack-player"><div class="mobile-friendly-snack" style="display: none"><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, StyleSheet, Text, View } <span class="hljs-keyword">from</span> <span class="hljs-string">"react-native"</span>;
|
||
|
||
<span class="hljs-keyword">export</span> <span class="hljs-keyword">default</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> =></span> {
|
||
<span class="hljs-keyword">if</span> (
|
||
<span class="hljs-keyword">this</span>.state.appState.match(<span class="hljs-regexp">/inactive|background/</span>) &&
|
||
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"><<span class="hljs-name">View</span> <span class="hljs-attr">style</span>=<span class="hljs-string">{styles.container}</span>></span>
|
||
<span class="hljs-tag"><<span class="hljs-name">Text</span>></span>Current state is: {this.state.appState}<span class="hljs-tag"></<span class="hljs-name">Text</span>></span>
|
||
<span class="hljs-tag"></<span class="hljs-name">View</span>></span></span>
|
||
);
|
||
}
|
||
}
|
||
|
||
<span class="hljs-keyword">const</span> styles = StyleSheet.create({
|
||
<span class="hljs-attr">container</span>: {
|
||
<span class="hljs-attr">flex</span>: <span class="hljs-number">1</span>,
|
||
<span class="hljs-attr">justifyContent</span>: <span class="hljs-string">"center"</span>,
|
||
<span class="hljs-attr">alignItems</span>: <span class="hljs-string">"center"</span>
|
||
}
|
||
});
|
||
</code></pre></div><div class="desktop-friendly-snack" style="margin-top: 15px; margin-bottom: 15px"><div
|
||
data-snack-name="AppState Class Component Example"
|
||
data-snack-description="Example usage"
|
||
data-snack-code="import%20React%2C%20%7B%20Component%20%7D%20from%20%22react%22%3B%0Aimport%20%7B%20AppState%2C%20StyleSheet%2C%20Text%2C%20View%20%7D%20from%20%22react-native%22%3B%0A%0Aexport%20default%20class%20AppStateExample%20extends%20Component%20%7B%0A%20%20state%20%3D%20%7B%0A%20%20%20%20appState%3A%20AppState.currentState%0A%20%20%7D%3B%0A%0A%20%20componentDidMount()%20%7B%0A%20%20%20%20AppState.addEventListener(%22change%22%2C%20this._handleAppStateChange)%3B%0A%20%20%7D%0A%0A%20%20componentWillUnmount()%20%7B%0A%20%20%20%20AppState.removeEventListener(%22change%22%2C%20this._handleAppStateChange)%3B%0A%20%20%7D%0A%0A%20%20_handleAppStateChange%20%3D%20nextAppState%20%3D%3E%20%7B%0A%20%20%20%20if%20(%0A%20%20%20%20%20%20this.state.appState.match(%2Finactive%7Cbackground%2F)%20%26%26%0A%20%20%20%20%20%20nextAppState%20%3D%3D%3D%20%22active%22%0A%20%20%20%20)%20%7B%0A%20%20%20%20%20%20console.log(%22App%20has%20come%20to%20the%20foreground!%22)%3B%0A%20%20%20%20%7D%0A%20%20%20%20this.setState(%7B%20appState%3A%20nextAppState%20%7D)%3B%0A%20%20%7D%3B%0A%0A%20%20render()%20%7B%0A%20%20%20%20return%20(%0A%20%20%20%20%20%20%3CView%20style%3D%7Bstyles.container%7D%3E%0A%20%20%20%20%20%20%20%20%3CText%3ECurrent%20state%20is%3A%20%7Bthis.state.appState%7D%3C%2FText%3E%0A%20%20%20%20%20%20%3C%2FView%3E%0A%20%20%20%20)%3B%0A%20%20%7D%0A%7D%0A%0Aconst%20styles%20%3D%20StyleSheet.create(%7B%0A%20%20container%3A%20%7B%0A%20%20%20%20flex%3A%201%2C%0A%20%20%20%20justifyContent%3A%20%22center%22%2C%0A%20%20%20%20alignItems%3A%20%22center%22%0A%20%20%7D%0A%7D)%3B%0A"
|
||
data-snack-platform="web"
|
||
data-snack-supported-platforms=ios,android,web
|
||
data-snack-preview="true"
|
||
style="
|
||
overflow: hidden;
|
||
background: #fafafa;
|
||
border: 1px solid rgba(0,0,0,.16);
|
||
border-radius: 4px;
|
||
height: 514px;
|
||
width: 100%;
|
||
"
|
||
></div></div></div><p><block class="endBlock syntax" /></p>
|
||
<p>This example will only ever appear to say "Current state is: active" 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>
|
||
<hr>
|
||
<h1><a class="anchor" aria-hidden="true" id="reference"></a><a href="#reference" aria-hidden="true" class="hash-link"><svg class="hash-link-icon" 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" id="events"></a><a href="#events" aria-hidden="true" class="hash-link"><svg class="hash-link-icon" 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>Events</h2>
|
||
<h3><a class="anchor" aria-hidden="true" id="change"></a><a href="#change" aria-hidden="true" class="hash-link"><svg class="hash-link-icon" 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>change</code></h3>
|
||
<p>This event is received when the app state has changed. The listener is called with one of <a href="appstate#app-states">the current app state values</a>.</p>
|
||
<h3><a class="anchor" aria-hidden="true" id="memorywarning"></a><a href="#memorywarning" aria-hidden="true" class="hash-link"><svg class="hash-link-icon" 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>memoryWarning</code></h3>
|
||
<p>This event is used in the need of throwing memory warning or releasing it.</p>
|
||
<h3><a class="anchor" aria-hidden="true" id="focus"></a><a href="#focus" aria-hidden="true" class="hash-link"><svg class="hash-link-icon" 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>focus</code></h3>
|
||
<p>[Android only] Received when the app gains focus (the user is interacting with the app).</p>
|
||
<h3><a class="anchor" aria-hidden="true" id="blur"></a><a href="#blur" aria-hidden="true" class="hash-link"><svg class="hash-link-icon" 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>blur</code></h3>
|
||
<p>[Android only] Received when the user is not actively interacting with the app. Useful in situations when the user pulls down the <a href="https://developer.android.com/guide/topics/ui/notifiers/notifications#bar-and-drawer">notification drawer</a>. <code>AppState</code> won't change but the <code>blur</code> event will get fired.</p>
|
||
<h2><a class="anchor" aria-hidden="true" id="methods"></a><a href="#methods" aria-hidden="true" class="hash-link"><svg class="hash-link-icon" 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" id="addeventlistener"></a><a href="#addeventlistener" aria-hidden="true" class="hash-link"><svg class="hash-link-icon" 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 language-jsx"><span class="token function">addEventListener</span><span class="token punctuation">(</span>type<span class="token punctuation">,</span> handler<span class="token punctuation">)</span><span class="token punctuation">;</span>
|
||
</code></pre>
|
||
<p>Add a handler to AppState changes by listening to the <code>change</code> event type and providing the handler</p>
|
||
<p>TODO: now that AppState is a subclass of NativeEventEmitter, we could deprecate <code>addEventListener</code> and <code>removeEventListener</code> and use <code>addListener</code> and <code>listener.remove()</code> directly. That will be a breaking change though, as both the method and event names are different (addListener events are currently required to be globally unique).</p>
|
||
<hr>
|
||
<h3><a class="anchor" aria-hidden="true" id="removeeventlistener"></a><a href="#removeeventlistener" aria-hidden="true" class="hash-link"><svg class="hash-link-icon" 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 language-jsx"><span class="token function">removeEventListener</span><span class="token punctuation">(</span>type<span class="token punctuation">,</span> handler<span class="token punctuation">)</span><span class="token punctuation">;</span>
|
||
</code></pre>
|
||
<p>Remove a handler by passing the <code>change</code> event type and the handler</p>
|
||
<h2><a class="anchor" aria-hidden="true" id="properties"></a><a href="#properties" aria-hidden="true" class="hash-link"><svg class="hash-link-icon" 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>Properties</h2>
|
||
<h3><a class="anchor" aria-hidden="true" id="currentstate"></a><a href="#currentstate" aria-hidden="true" class="hash-link"><svg class="hash-link-icon" 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>currentState</code></h3>
|
||
<pre><code class="hljs css language-jsx">AppState<span class="token punctuation">.</span>currentState<span class="token punctuation">;</span>
|
||
</code></pre>
|
||
</span></div></article></div><div class="docs-prevnext"><a class="docs-prev button" href="/docs/appregistry"><span class="arrow-prev">← </span><span class="function-name-prevnext">AppRegistry</span></a><a class="docs-next button" href="/docs/devsettings"><span class="function-name-prevnext">DevSettings</span><span class="arrow-next"> →</span></a></div></div></div><nav class="onPageNav"><ul class="toc-headings"><li><a href="#basic-usage">Basic Usage</a></li><li><a href="#events">Events</a><ul class="toc-headings"><li><a href="#change"><code>change</code></a></li><li><a href="#memorywarning"><code>memoryWarning</code></a></li><li><a href="#focus"><code>focus</code></a></li><li><a href="#blur"><code>blur</code></a></li></ul></li><li><a href="#methods">Methods</a><ul class="toc-headings"><li><a href="#addeventlistener"><code>addEventListener()</code></a></li><li><a href="#removeeventlistener"><code>removeEventListener()</code></a></li></ul></li><li><a href="#properties">Properties</a><ul class="toc-headings"><li><a href="#currentstate"><code>currentState</code></a></li></ul></li></ul></nav></div><footer class="nav-footer" id="footer"><section class="sitemap"><div><h5>Docs</h5><a href="/docs/getting-started">Getting Started</a><a href="/docs/tutorial">Tutorial</a><a href="/docs/components-and-apis">Components and APIs</a><a href="/docs/more-resources">More Resources</a></div><div><h5>Community</h5><a href="/help">The React Native Community</a><a href="/showcase">Who's using React Native?</a><a href="https://stackoverflow.com/questions/tagged/react-native" target="_blank">Ask Questions on Stack Overflow</a><a href="https://github.com/facebook/react-native/blob/master/CONTRIBUTING.md">Contributor Guide</a><a href="https://dev.to/t/reactnative" target="_blank">DEV Community</a></div><div><h5>More Resources</h5><a href="/blog">Blog</a><a href="https://twitter.com/reactnative" target="_blank">Twitter</a><a href="https://github.com/facebook/react-native" target="_blank">GitHub</a><a href="https://reactjs.org" target="_blank">React</a></div></section><a href="https://code.facebook.com/projects/" target="_blank" class="fbOpenSource"><img src="/img/oss_logo.png" alt="Facebook Open Source" width="170" height="45"/></a><section class="copyright">Copyright © 2020 Facebook Inc.</section></footer></div><script type="text/javascript" src="https://cdn.jsdelivr.net/docsearch.js/1/docsearch.min.js"></script><script>window.fbAsyncInit = function() {FB.init({appId:'1677033832619985',xfbml:true,version:'v2.7'});};(function(d, s, id){var js, fjs = d.getElementsByTagName(s)[0];if (d.getElementById(id)) {return;}js = d.createElement(s); js.id = id;js.src = '//connect.facebook.net/en_US/sdk.js';fjs.parentNode.insertBefore(js, fjs);}(document, 'script','facebook-jssdk'));
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||
</script><script>window.twttr=(function(d,s, id){var js,fjs=d.getElementsByTagName(s)[0],t=window.twttr||{};if(d.getElementById(id))return t;js=d.createElement(s);js.id=id;js.src='https://platform.twitter.com/widgets.js';fjs.parentNode.insertBefore(js, fjs);t._e = [];t.ready = function(f) {t._e.push(f);};return t;}(document, 'script', 'twitter-wjs'));</script><script>
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document.addEventListener('keyup', function(e) {
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if (e.target !== document.body) {
|
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return;
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||
}
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// keyCode for '/' (slash)
|
||
if (e.keyCode === 191) {
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const search = document.getElementById('search_input_react');
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||
search && search.focus();
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}
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});
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</script><script>
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var search = docsearch({
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algoliaOptions: {"facetFilters":["tags:0.62"],"hitsPerPage":5}
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});
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</script></body></html> |