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Hector Ramos
31 lines
22 KiB
HTML
31 lines
22 KiB
HTML
<!DOCTYPE html><html><head><title>BackAndroid</title><meta charset="utf-8"><meta http-equiv="X-UA-Compatible" content="IE=edge,chrome=1"><meta name="viewport" content="width=device-width"><meta property="fb:app_id" content="1677033832619985"><meta property="fb:admins" content="121800083"><meta property="og:site_name" content="React Native"><meta property="og:title" content="BackAndroid"><meta property="og:url" content="https://facebook.github.io/react-native/index.html"><meta property="og:image" content="https://facebook.github.io/react-native/img/opengraph.png"><meta property="og:description" content="A framework for building native apps using React"><meta name="twitter:site" content="@reactnative"><meta name="twitter:card" content="summary_large_image"><meta property="og:type" content="website"><base href="/react-native/"><link rel="stylesheet" href="https://cdn.jsdelivr.net/docsearch.js/1/docsearch.min.css"><link rel="shortcut icon" href="img/favicon.png?2"><link rel="stylesheet" href="css/react-native.css"><link rel="alternate" type="application/rss+xml" title="React Native Blog" href="https://facebook.github.io/react-native/blog/feed.xml"><link href="//cdn-images.mailchimp.com/embedcode/horizontal-slim-10_7.css" rel="stylesheet" type="text/css"><script type="text/javascript" src="//use.typekit.net/vqa1hcx.js"></script><script type="text/javascript">try{Typekit.load();}catch(e){}</script></head><body><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'));</script><script>window.twttr=(function(d,s, id){var js,fjs=d.getElementsByTagName(s)[0],t=window.twttr||{};if(d.getElementById(id))return 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class="">GitHub</a></li><li><a href="http://facebook.github.io/react" class="">React</a></li></ul></div></div></div><section class="content wrap documentationContent"><div class="nav-docs"><div class="nav-docs-viewport"><div class="nav-docs-section"><h3>The Basics</h3><ul><li><a style="margin-left:10px;" class="" href="docs/getting-started.html">Getting Started</a></li><li><a style="margin-left:10px;" class="" href="docs/tutorial.html">Tutorial</a></li><li><a style="margin-left:10px;" class="" href="docs/props.html">Props</a></li><li><a style="margin-left:10px;" class="" href="docs/state.html">State</a></li><li><a style="margin-left:10px;" class="" href="docs/style.html">Style</a></li><li><a style="margin-left:10px;" class="" href="docs/height-and-width.html">Height and Width</a></li><li><a style="margin-left:10px;" class="" href="docs/flexbox.html">Layout with Flexbox</a></li><li><a style="margin-left:10px;" class="" href="docs/handling-text-input.html">Handling Text Input</a></li><li><a style="margin-left:10px;" class="" href="docs/using-a-scrollview.html">Using a ScrollView</a></li><li><a style="margin-left:10px;" class="" href="docs/using-a-listview.html">Using a ListView</a></li><li><a style="margin-left:10px;" class="" href="docs/network.html">Networking</a></li><li><a style="margin-left:10px;" class="" href="docs/more-resources.html">More Resources</a></li></ul></div><div class="nav-docs-section"><h3>Guides</h3><ul><li><a style="margin-left:10px;" class="" href="docs/handling-touches.html">Handling Touches</a></li><li><a style="margin-left:10px;" class="" href="docs/animations.html">Animations</a></li><li><a style="margin-left:10px;" class="" href="docs/navigation.html">Navigation</a></li><li><a style="margin-left:10px;" class="" href="docs/images.html">Images</a></li><li><a style="margin-left:10px;" class="" href="docs/colors.html">Colors</a></li><li><a style="margin-left:10px;" class="" href="docs/platform-specific-code.html">Platform Specific Code</a></li><li><a style="margin-left:10px;" class="" href="docs/debugging.html">Debugging</a></li><li><a style="margin-left:10px;" class="" href="docs/accessibility.html">Accessibility</a></li><li><a style="margin-left:10px;" class="" href="docs/timers.html">Timers</a></li><li><a style="margin-left:10px;" class="" href="docs/javascript-environment.html">JavaScript Environment</a></li><li><a style="margin-left:10px;" class="" href="docs/direct-manipulation.html">Direct Manipulation</a></li><li><a style="margin-left:10px;" class="" href="docs/performance.html">Performance</a></li><li><a style="margin-left:10px;" class="" href="docs/gesture-responder-system.html">Gesture Responder System</a></li><li><a style="margin-left:10px;" class="" href="docs/testing.html">Testing</a></li><li><a style="margin-left:10px;" class="" href="docs/understanding-cli.html">Understanding the CLI</a></li><li><a style="margin-left:10px;" class="" href="docs/integration-with-existing-apps.html">Integration With Existing Apps</a></li><li><a style="margin-left:10px;" class="" href="docs/running-on-device.html">Running On Device</a></li><li><a style="margin-left:10px;" class="" href="docs/upgrading.html">Upgrading</a></li></ul></div><div class="nav-docs-section"><h3>Guides (iOS)</h3><ul><li><a style="margin-left:10px;" class="" href="docs/native-modules-ios.html">Native Modules</a></li><li><a style="margin-left:10px;" class="" href="docs/native-components-ios.html">Native UI Components</a></li><li><a style="margin-left:10px;" class="" href="docs/linking-libraries-ios.html">Linking Libraries</a></li><li><a style="margin-left:10px;" class="" href="docs/running-on-simulator-ios.html">Running On Simulator</a></li><li><a style="margin-left:10px;" class="" href="docs/communication-ios.html">Communication between native and React Native</a></li></ul></div><div class="nav-docs-section"><h3>Guides (Android)</h3><ul><li><a style="margin-left:10px;" class="" href="docs/native-modules-android.html">Native Modules</a></li><li><a style="margin-left:10px;" class="" href="docs/native-components-android.html">Native UI Components</a></li><li><a style="margin-left:10px;" class="" href="docs/headless-js-android.html">Headless JS</a></li><li><a style="margin-left:10px;" class="" href="docs/signed-apk-android.html">Generating Signed APK</a></li><li><a style="margin-left:10px;" class="" href="docs/android-building-from-source.html">Building React Native from source</a></li></ul></div><div class="nav-docs-section"><h3>components</h3><ul><li><a style="margin-left:10px;" class="" href="docs/activityindicator.html">ActivityIndicator</a></li><li><a style="margin-left:10px;" class="" href="docs/button.html">Button</a></li><li><a style="margin-left:10px;" class="" href="docs/datepickerios.html">DatePickerIOS</a></li><li><a style="margin-left:10px;" class="" href="docs/drawerlayoutandroid.html">DrawerLayoutAndroid</a></li><li><a style="margin-left:10px;" class="" href="docs/image.html">Image</a></li><li><a style="margin-left:10px;" class="" href="docs/keyboardavoidingview.html">KeyboardAvoidingView</a></li><li><a style="margin-left:10px;" class="" href="docs/listview.html">ListView</a></li><li><a style="margin-left:10px;" class="" href="docs/mapview.html">MapView</a></li><li><a style="margin-left:10px;" class="" href="docs/modal.html">Modal</a></li><li><a style="margin-left:10px;" class="" href="docs/navigator.html">Navigator</a></li><li><a style="margin-left:10px;" class="" href="docs/navigatorios.html">NavigatorIOS</a></li><li><a style="margin-left:10px;" class="" href="docs/picker.html">Picker</a></li><li><a style="margin-left:10px;" class="" href="docs/pickerios.html">PickerIOS</a></li><li><a style="margin-left:10px;" class="" href="docs/progressbarandroid.html">ProgressBarAndroid</a></li><li><a style="margin-left:10px;" class="" href="docs/progressviewios.html">ProgressViewIOS</a></li><li><a style="margin-left:10px;" class="" href="docs/refreshcontrol.html">RefreshControl</a></li><li><a style="margin-left:10px;" class="" href="docs/scrollview.html">ScrollView</a></li><li><a style="margin-left:10px;" class="" href="docs/segmentedcontrolios.html">SegmentedControlIOS</a></li><li><a style="margin-left:10px;" class="" href="docs/slider.html">Slider</a></li><li><a style="margin-left:10px;" class="" href="docs/snapshotviewios.html">SnapshotViewIOS</a></li><li><a style="margin-left:10px;" class="" href="docs/statusbar.html">StatusBar</a></li><li><a style="margin-left:10px;" class="" href="docs/switch.html">Switch</a></li><li><a style="margin-left:10px;" class="" href="docs/tabbarios.html">TabBarIOS</a></li><li><a style="margin-left:10px;" class="" href="docs/tabbarios-item.html">TabBarIOS.Item</a></li><li><a style="margin-left:10px;" class="" href="docs/text.html">Text</a></li><li><a style="margin-left:10px;" class="" href="docs/textinput.html">TextInput</a></li><li><a style="margin-left:10px;" class="" href="docs/toolbarandroid.html">ToolbarAndroid</a></li><li><a style="margin-left:10px;" class="" href="docs/touchablehighlight.html">TouchableHighlight</a></li><li><a style="margin-left:10px;" class="" href="docs/touchablenativefeedback.html">TouchableNativeFeedback</a></li><li><a style="margin-left:10px;" class="" href="docs/touchableopacity.html">TouchableOpacity</a></li><li><a style="margin-left:10px;" class="" href="docs/touchablewithoutfeedback.html">TouchableWithoutFeedback</a></li><li><a style="margin-left:10px;" class="" href="docs/view.html">View</a></li><li><a style="margin-left:10px;" class="" href="docs/viewpagerandroid.html">ViewPagerAndroid</a></li><li><a style="margin-left:10px;" class="" href="docs/webview.html">WebView</a></li></ul></div><div class="nav-docs-section"><h3>APIs</h3><ul><li><a style="margin-left:10px;" class="" href="docs/actionsheetios.html">ActionSheetIOS</a></li><li><a style="margin-left:10px;" class="" href="docs/adsupportios.html">AdSupportIOS</a></li><li><a style="margin-left:10px;" class="" href="docs/alert.html">Alert</a></li><li><a style="margin-left:10px;" class="" href="docs/alertios.html">AlertIOS</a></li><li><a style="margin-left:10px;" class="" href="docs/animated.html">Animated</a></li><li><a style="margin-left:10px;" class="" href="docs/appregistry.html">AppRegistry</a></li><li><a style="margin-left:10px;" class="" href="docs/appstate.html">AppState</a></li><li><a style="margin-left:10px;" class="" href="docs/asyncstorage.html">AsyncStorage</a></li><li><a style="margin-left:10px;" class="active" href="docs/backandroid.html">BackAndroid</a></li><li><a style="margin-left:10px;" class="" href="docs/cameraroll.html">CameraRoll</a></li><li><a style="margin-left:10px;" class="" href="docs/clipboard.html">Clipboard</a></li><li><a style="margin-left:10px;" class="" href="docs/datepickerandroid.html">DatePickerAndroid</a></li><li><a style="margin-left:10px;" class="" href="docs/dimensions.html">Dimensions</a></li><li><a style="margin-left:10px;" class="" href="docs/easing.html">Easing</a></li><li><a style="margin-left:10px;" class="" href="docs/geolocation.html">Geolocation</a></li><li><a style="margin-left:10px;" class="" href="docs/imageeditor.html">ImageEditor</a></li><li><a style="margin-left:10px;" class="" href="docs/imagepickerios.html">ImagePickerIOS</a></li><li><a style="margin-left:10px;" class="" href="docs/imagestore.html">ImageStore</a></li><li><a style="margin-left:10px;" class="" href="docs/interactionmanager.html">InteractionManager</a></li><li><a style="margin-left:10px;" class="" href="docs/keyboard.html">Keyboard</a></li><li><a style="margin-left:10px;" class="" href="docs/layoutanimation.html">LayoutAnimation</a></li><li><a style="margin-left:10px;" class="" href="docs/linking.html">Linking</a></li><li><a style="margin-left:10px;" class="" href="docs/nativemethodsmixin.html">NativeMethodsMixin</a></li><li><a style="margin-left:10px;" class="" href="docs/netinfo.html">NetInfo</a></li><li><a style="margin-left:10px;" class="" href="docs/panresponder.html">PanResponder</a></li><li><a style="margin-left:10px;" class="" href="docs/permissionsandroid.html">PermissionsAndroid</a></li><li><a style="margin-left:10px;" class="" href="docs/pixelratio.html">PixelRatio</a></li><li><a style="margin-left:10px;" class="" href="docs/pushnotificationios.html">PushNotificationIOS</a></li><li><a style="margin-left:10px;" class="" href="docs/settings.html">Settings</a></li><li><a style="margin-left:10px;" class="" href="docs/share.html">Share</a></li><li><a style="margin-left:10px;" class="" href="docs/statusbarios.html">StatusBarIOS</a></li><li><a style="margin-left:10px;" class="" href="docs/stylesheet.html">StyleSheet</a></li><li><a style="margin-left:10px;" class="" href="docs/systrace.html">Systrace</a></li><li><a style="margin-left:10px;" class="" href="docs/timepickerandroid.html">TimePickerAndroid</a></li><li><a style="margin-left:10px;" class="" href="docs/toastandroid.html">ToastAndroid</a></li><li><a style="margin-left:10px;" class="" href="docs/vibration.html">Vibration</a></li><li><a style="margin-left:10px;" class="" href="docs/vibrationios.html">VibrationIOS</a></li><li><a style="margin-left:10px;" class="" href="docs/layout-props.html">Layout Props</a></li><li><a style="margin-left:10px;" class="" href="docs/shadow-props.html">Shadow Props</a></li></ul></div></div></div><div class="inner-content"><a id="content"></a><h1><a class="anchor" name="backandroid"></a>BackAndroid <a class="hash-link" href="docs/backandroid.html#backandroid">#</a></h1><div><div><p>Detect hardware back button presses, and programmatically invoke the default back button
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functionality to exit the app if there are no listeners or if none of the listeners return true.
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The event subscriptions are called in reverse order (i.e. last registered subscription first),
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and if one subscription returns true then subscriptions registered earlier will not be called.</p><p>Example:</p><div class="prism language-javascript">BackAndroid<span class="token punctuation">.</span><span class="token function">addEventListener<span class="token punctuation">(</span></span><span class="token string">'hardwareBackPress'</span><span class="token punctuation">,</span> <span class="token keyword">function</span><span class="token punctuation">(</span><span class="token punctuation">)</span> <span class="token punctuation">{</span>
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<span class="token comment" spellcheck="true"> // this.onMainScreen and this.goBack are just examples, you need to use your own implementation here
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</span><span class="token comment" spellcheck="true"> // Typically you would use the navigator here to go to the last state.
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</span>
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<span class="token keyword">if</span> <span class="token punctuation">(</span><span class="token operator">!</span><span class="token keyword">this</span><span class="token punctuation">.</span><span class="token function">onMainScreen<span class="token punctuation">(</span></span><span class="token punctuation">)</span><span class="token punctuation">)</span> <span class="token punctuation">{</span>
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<span class="token keyword">this</span><span class="token punctuation">.</span><span class="token function">goBack<span class="token punctuation">(</span></span><span class="token punctuation">)</span><span class="token punctuation">;</span>
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<span class="token keyword">return</span> <span class="token boolean">true</span><span class="token punctuation">;</span>
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<span class="token punctuation">}</span>
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<span class="token keyword">return</span> <span class="token boolean">false</span><span class="token punctuation">;</span>
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<span class="token punctuation">}</span><span class="token punctuation">)</span><span class="token punctuation">;</span></div></div><span><h3><a class="anchor" name="methods"></a>Methods <a class="hash-link" href="docs/backandroid.html#methods">#</a></h3><div class="props"><div class="prop"><h4 class="methodTitle"><a class="anchor" name="exitapp"></a><span class="methodType">static </span>exitApp<span class="methodType">()</span> <a class="hash-link" href="docs/backandroid.html#exitapp">#</a></h4></div><div class="prop"><h4 class="methodTitle"><a class="anchor" name="addeventlistener"></a><span class="methodType">static </span>addEventListener<span class="methodType">(eventName, handler)</span> <a class="hash-link" href="docs/backandroid.html#addeventlistener">#</a></h4></div><div class="prop"><h4 class="methodTitle"><a class="anchor" name="removeeventlistener"></a><span class="methodType">static </span>removeEventListener<span class="methodType">(eventName, handler)</span> <a class="hash-link" href="docs/backandroid.html#removeeventlistener">#</a></h4></div></div></span></div><p class="edit-page-block">You can <a target="_blank" href="https://github.com/facebook/react-native/blob/master/Libraries/Utilities/BackAndroid.android.js">edit the content above on GitHub</a> and send us a pull request!</p><div class="docs-prevnext"><a class="docs-prev" href="docs/asyncstorage.html#content">← Prev</a><a class="docs-next" href="docs/cameraroll.html#content">Next →</a></div></div></section><footer class="nav-footer"><section class="sitemap"><a href="/react-native" class="nav-home"><img src="img/header_logo.png" alt="React Native" width="66" height="58"></a><div><h5><a href="docs/">Docs</a></h5><a href="docs/getting-started.html">Getting Started</a><a href="docs/tutorial.html">Tutorial</a><a href="docs/integration-with-existing-apps.html">Integration With Existing Apps</a><a href="docs/more-resources.html">More Resources</a></div><div><h5><a href="/react-native/support.html">Community</a></h5><a href="/react-native/showcase.html">Showcase</a><a href="http://www.meetup.com/topics/react-native/" target="_blank">Upcoming Events</a><a href="https://www.facebook.com/groups/react.native.community" target="_blank">Facebook Group</a><a href="https://twitter.com/reactnative" target="_blank">Twitter</a></div><div><h5><a href="/react-native/support.html">Help</a></h5><a href="http://stackoverflow.com/questions/tagged/react-native" target="_blank">Stack Overflow</a><a href="https://discord.gg/0ZcbPKXt5bZjGY5n">Reactiflux Chat</a><a href="/react-native/versions.html" target="_blank">Latest Releases</a><a href="https://react-native.canny.io/feature-requests" target="_blank">Feature Requests</a></div><div><h5>More</h5><a href="/react-native/blog">Blog</a><a href="https://github.com/facebook/react-native" target="_blank">GitHub</a><a href="http://facebook.github.io/react/" target="_blank">React</a></div></section><section class="newsletter"><div id="mc_embed_signup"><form action="//reactnative.us10.list-manage.com/subscribe/post?u=db0dd948e2b729ee62625b1a8&id=47cd41008f" method="post" id="mc-embedded-subscribe-form" name="mc-embedded-subscribe-form" class="validate" target="_blank" novalidate><div id="mc_embed_signup_scroll"><label for="mce-EMAIL"><h5>Get the React Native Newsletter</h5></label><input type="email" value="" name="EMAIL" class="email" id="mce-EMAIL" placeholder="email address" required><div style="position:absolute;left:-5000px;" aria-hidden="true"><input type="text" name="b_db0dd948e2b729ee62625b1a8_47cd41008f" tabindex="-1" value=""></div><div class="clear"><input type="submit" value="Sign up" name="subscribe" id="mc-embedded-subscribe" class="button"></div></div></form></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 © 2017 Facebook Inc.</section></footer></div><div id="fb-root"></div><script type="text/javascript" src="https://cdn.jsdelivr.net/docsearch.js/1/docsearch.min.js"></script><script>
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