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Expo Barometer iconExpo Barometer

GitHub

npm

A library that provides access to device's barometer sensor.

Android

Barometer from expo-sensors provides access to the device barometer sensor to respond to changes in air pressure, which is measured in hectopascals (hPa).

Installation

Terminal
npx expo install expo-sensors

If you're installing this in a bare React Native app, you should also follow these additional installation instructions.

Usage

Basic Barometer usage
import React, { useState } from 'react';
import { StyleSheet, Text, TouchableOpacity, View, Platform } from 'react-native';
import { Barometer } from 'expo-sensors';

export default function App() {
  const [{ pressure, relativeAltitude }, setData] = useState({ pressure: 0, relativeAltitude: 0 });
  const [subscription, setSubscription] = useState(null);

  const toggleListener = () => {
    subscription ? unsubscribe() : subscribe();
  };

  const subscribe = () => {
    setSubscription(Barometer.addListener(setData));
  };

  const unsubscribe = () => {
    subscription && subscription.remove();
    setSubscription(null);
  };

  return (
    <View style={styles.wrapper}>
      <Text>Barometer: Listener {subscription ? 'ACTIVE' : 'INACTIVE'}</Text>
      <Text>Pressure: {pressure} hPa</Text>
      <Text>
        Relative Altitude:{' '}
        {Platform.OS === 'ios' ? `${relativeAltitude} m` : `Only available on iOS`}
      </Text>
      <TouchableOpacity onPress={toggleListener} style={styles.button}>
        <Text>Toggle listener</Text>
      </TouchableOpacity>
    </View>
  );
}

const styles = StyleSheet.create({
  button: {
    justifyContent: 'center',
    alignItems: 'center',
    backgroundColor: '#eee',
    padding: 10,
    marginTop: 15,
  },
  wrapper: {
    flex: 1,
    alignItems: 'stretch',
    justifyContent: 'center',
    paddingHorizontal: 20,
  },
});

API

import { Barometer } from 'expo-sensors';

Classes

Only for:
Android
iOS

Barometer

Type: Class extends DeviceSensor<BarometerMeasurement>

Barometer Methods

addListener(listener)

NameTypeDescription
listenerListener<BarometerMeasurement>

A callback that is invoked when a barometer update is available. When invoked, the listener is provided with a single argument that is BarometerMeasurement.


Subscribe for updates to the barometer.

Returns:

Subscription

A subscription that you can call remove() on when you would like to unsubscribe the listener.

Example

const subscription = Barometer.addListener(({ pressure, relativeAltitude }) => {
  console.log({ pressure, relativeAltitude });
});

getListenerCount()

Returns the registered listeners count.

Returns:

number

getPermissionsAsync()

Checks user's permissions for accessing sensor.

hasListeners()

Returns boolean which signifies if sensor has any listeners registered.

Returns:

boolean

isAvailableAsync()

You should always check the sensor availability before attempting to use it.

Check the availability of the device barometer. Requires at least Android 2.3 (API Level 9) and iOS 8.

Returns:

Promise<boolean>

A promise that resolves to a boolean denoting the availability of the sensor.

removeAllListeners()

Removes all registered listeners.

Returns:

void

removeSubscription(subscription)

NameTypeDescription
subscriptionSubscription

A subscription to remove.


Removes the given subscription.

Returns:

void

requestPermissionsAsync()

Asks the user to grant permissions for accessing sensor.

setUpdateInterval(intervalMs)

NameTypeDescription
intervalMsnumber

Desired interval in milliseconds between sensor updates.

Starting from Android 12 (API level 31), the system has a 200ms limit for each sensor updates.

If you need an update interval less than 200ms, you should:

  • add android.permission.HIGH_SAMPLING_RATE_SENSORS to app.json permissions field
  • or if you are using bare workflow, add <uses-permission android:name="android.permission.HIGH_SAMPLING_RATE_SENSORS"/> to AndroidManifest.xml.

Set the sensor update interval.

Returns:

void

Interfaces

PermissionResponse

An object obtained by permissions get and request functions.

PermissionResponse Properties

NameTypeDescription
canAskAgainboolean

Indicates if user can be asked again for specific permission. If not, one should be directed to the Settings app in order to enable/disable the permission.

expiresPermissionExpiration

Determines time when the permission expires.

grantedboolean

A convenience boolean that indicates if the permission is granted.

statusPermissionStatus

Determines the status of the permission.


Types

BarometerMeasurement

The altitude data returned from the native sensors.

NameTypeDescription
pressurenumber

Measurement in hectopascals (hPa).

relativeAltitude
(optional)
number
Only for:
iOS

Measurement in meters (m).

PermissionExpiration

Literal Type: multiple types

Permission expiration time. Currently, all permissions are granted permanently.

Acceptable values are: 'never' | number

Subscription

NameTypeDescription
remove() => void

A method to unsubscribe the listener.

Enums

PermissionStatus

PermissionStatus Values

DENIED

PermissionStatus.DENIED = "denied"

User has denied the permission.

GRANTED

PermissionStatus.GRANTED = "granted"

User has granted the permission.

UNDETERMINED

PermissionStatus.UNDETERMINED = "undetermined"

User hasn't granted or denied the permission yet.

Units and providers

OSUnitsProviderDescription
iOShPaCMAltimeterAltitude events reflect the change in the current altitude, not the absolute altitude.
AndroidhPaSensor.TYPE_PRESSUREMonitoring air pressure changes.
WebThis sensor is not available on the web and cannot be accessed. An UnavailabilityError will be thrown if you attempt to get data.