React Native

0.53-RC

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Building For TV Devices

TV devices support has been implemented with the intention of making existing React Native applications "just work" on Apple TV and Android TV, with few or no changes needed in the JavaScript code for the applications.

The RNTester app supports Apple TV; use the RNTester-tvOS build target to build for tvOS.

Build changes

  • Native layer: React Native Xcode projects all now have Apple TV build targets, with names ending in the string '-tvOS'.

  • react-native init: New React Native projects created with react-native init will have Apple TV target automatically created in their XCode projects.

  • JavaScript layer: Support for Apple TV has been added to Platform.ios.js. You can check whether code is running on AppleTV by doing

var Platform = require('Platform');
var running_on_tv = Platform.isTV;

// If you want to be more specific and only detect devices running tvOS
// (but no Android TV devices) you can use:
var running_on_apple_tv = Platform.isTVOS;

Build changes

  • Native layer: To run React Native project on Android TV make sure to make the following changes to AndroidManifest.xml
  <!-- Add custom banner image to display as Android TV launcher icon -->
 <application
  ...
  android:banner="@drawable/tv_banner"
  >
    ...
    <intent-filter>
      ...
      <!-- Needed to properly create a launch intent when running on Android TV -->
      <category android:name="android.intent.category.LEANBACK_LAUNCHER"/>
    </intent-filter>
    ...
  </application>
  • JavaScript layer: Support for Android TV has been added to Platform.android.js. You can check whether code is running on Android TV by doing
var Platform = require('Platform');
var running_on_android_tv = Platform.isTV;

Code changes

  • General support for tvOS: Apple TV specific changes in native code are all wrapped by the TARGET_OS_TV define. These include changes to suppress APIs that are not supported on tvOS (e.g. web views, sliders, switches, status bar, etc.), and changes to support user input from the TV remote or keyboard.

  • Common codebase: Since tvOS and iOS share most Objective-C and JavaScript code in common, most documentation for iOS applies equally to tvOS.

  • Access to touchable controls: When running on Apple TV, the native view class is RCTTVView, which has additional methods to make use of the tvOS focus engine. The Touchable mixin has code added to detect focus changes and use existing methods to style the components properly and initiate the proper actions when the view is selected using the TV remote, so TouchableHighlight and TouchableOpacity will "just work". In particular:

    • touchableHandleActivePressIn will be executed when the touchable view goes into focus
    • touchableHandleActivePressOut will be executed when the touchable view goes out of focus
    • touchableHandlePress will be executed when the touchable view is actually selected by pressing the "select" button on the TV remote.

  • Access to touchable controls: When running on Android TV the Android framework will automatically apply a directional navigation scheme based on relative position of focusable elements in your views. The Touchable mixin has code added to detect focus changes and use existing methods to style the components properly and initiate the proper actions when the view is selected using the TV remote, so TouchableHighlight, TouchableOpacity and TouchableNativeFeedback will "just work". In particular:

    • touchableHandleActivePressIn will be executed when the touchable view goes into focus
    • touchableHandleActivePressOut will be executed when the touchable view goes out of focus
    • touchableHandlePress will be executed when the touchable view is actually selected by pressing the "select" button on the TV remote.

  • TV remote/keyboard input: A new native class, RCTTVRemoteHandler, sets up gesture recognizers for TV remote events. When TV remote events occur, this class fires notifications that are picked up by RCTTVNavigationEventEmitter (a subclass of RCTEventEmitter), that fires a JS event. This event will be picked up by instances of the TVEventHandler JavaScript object. Application code that needs to implement custom handling of TV remote events can create an instance of TVEventHandler and listen for these events, as in the following code:

  • TV remote/keyboard input: A new native class, ReactAndroidTVRootViewHelper, sets up key events handlers for TV remote events. When TV remote events occur, this class fires a JS event. This event will be picked up by instances of the TVEventHandler JavaScript object. Application code that needs to implement custom handling of TV remote events can create an instance of TVEventHandler and listen for these events, as in the following code:

var TVEventHandler = require('TVEventHandler');

.
.
.

class Game2048 extends React.Component {
  _tvEventHandler: any;

  _enableTVEventHandler() {
    this._tvEventHandler = new TVEventHandler();
    this._tvEventHandler.enable(this, function(cmp, evt) {
      if (evt && evt.eventType === 'right') {
        cmp.setState({board: cmp.state.board.move(2)});
      } else if(evt && evt.eventType === 'up') {
        cmp.setState({board: cmp.state.board.move(1)});
      } else if(evt && evt.eventType === 'left') {
        cmp.setState({board: cmp.state.board.move(0)});
      } else if(evt && evt.eventType === 'down') {
        cmp.setState({board: cmp.state.board.move(3)});
      } else if(evt && evt.eventType === 'playPause') {
        cmp.restartGame();
      }
    });
  }

  _disableTVEventHandler() {
    if (this._tvEventHandler) {
      this._tvEventHandler.disable();
      delete this._tvEventHandler;
    }
  }

  componentDidMount() {
    this._enableTVEventHandler();
  }

  componentWillUnmount() {
    this._disableTVEventHandler();
  }

  • Dev Menu support: On the simulator, cmd-D will bring up the developer menu, just like on iOS. To bring it up on a real Apple TV device, make a long press on the play/pause button on the remote. (Please do not shake the Apple TV device, that will not work :) )

  • TV remote animations: RCTTVView native code implements Apple-recommended parallax animations to help guide the eye as the user navigates through views. The animations can be disabled or adjusted with new optional view properties.

  • Back navigation with the TV remote menu button: The BackHandler component, originally written to support the Android back button, now also supports back navigation on the Apple TV using the menu button on the TV remote.

  • TabBarIOS behavior: The TabBarIOS component wraps the native UITabBar API, which works differently on Apple TV. To avoid jittery rerendering of the tab bar in tvOS (see this issue), the selected tab bar item can only be set from Javascript on initial render, and is controlled after that by the user through native code.

  • Dev Menu support: On the simulator, cmd-M will bring up the developer menu, just like on Android. To bring it up on a real Android TV device, make a long press on the play/pause button on the remote. (Please do not shake the Android TV device, that will not work :) )

  • Known issues:

    • ListView scrolling. The issue can be easily worked around by setting removeClippedSubviews to false in ListView and similar components. For more discussion of this issue, see this PR.

  • Known issues:

    • InputText components do not work for now (i.e. they cannot receive focus).
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