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React Native中文文档0.51版

Sometimes it's useful to know whether or not the device has a screen reader that is currently active. The AccessibilityInfo API is designed for this purpose. You can use it to query the current state of the screen reader as well as to register to be notified when the state of the screen reader changes.

Here's a small example illustrating how to use AccessibilityInfo:

class ScreenReaderStatusExample extends React.Component {
  state = {
    screenReaderEnabled: false,
  }

  componentDidMount() {
    AccessibilityInfo.addEventListener(
      'change',
      this._handleScreenReaderToggled
    );
    AccessibilityInfo.fetch().done((isEnabled) => {
      this.setState({
        screenReaderEnabled: isEnabled
      });
    });
  }

  componentWillUnmount() {
    AccessibilityInfo.removeEventListener(
      'change',
      this._handleScreenReaderToggled
    );
  }

  _handleScreenReaderToggled = (isEnabled) => {
    this.setState({
      screenReaderEnabled: isEnabled,
    });
  }

  render() {
    return (
      <View>
        <Text>
          The screen reader is {this.state.screenReaderEnabled ? 'enabled' : 'disabled'}.
        </Text>
      </View>
    );
  }
}

方法

static fetch() #

Query whether a screen reader is currently enabled. Returns a promise which resolves to a boolean. The result is true when a screen reader is enabled and false otherwise.

static addEventListener(eventName, handler) #

Add an event handler. Supported events:

  • change: Fires when the state of the screen reader changes. The argument to the event handler is a boolean. The boolean is true when a screen reader is enabled and false otherwise.
  • announcementFinished: iOS-only event. Fires when the screen reader has finished making an announcement. The argument to the event handler is a dictionary with these keys:
    • announcement: The string announced by the screen reader.
    • success: A boolean indicating whether the announcement was successfully made.

static setAccessibilityFocus(reactTag) #

iOS-Only. Set accessibility focus to a react component.

static announceForAccessibility(announcement) #

iOS-Only. Post a string to be announced by the screen reader.

static removeEventListener(eventName, handler) #

Remove an event handler.

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