This is documentation for the next SDK version. For up-to-date documentation, see the latest version (SDK 51).
A library that provides access to device's barometer sensor.
GitHub
npm
Barometer
from expo-sensors
provides access to the device barometer sensor to respond to changes in air pressure, which is measured in hectopascals (hPa
).
-
npx expo install expo-sensors
If you are installing this in an existing React Native app (bare workflow), start by installing expo
in your project. Then, follow the additional instructions as mentioned by library's README under "Installation in bare React Native projects" section.
import { 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,
},
});
import { Barometer } from 'expo-sensors';
Barometer
Type: Class extends DeviceSensor<BarometerMeasurement>
Barometer Methods
addListener(listener)
Name | Type | Description |
---|---|---|
listener | Listener<BarometerMeasurement> | A callback that is invoked when a barometer update is available. When invoked, the listener is provided with a single argument that is |
Subscribe for updates to the barometer.
EventSubscription
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 });
});
hasListeners()
Returns boolean which signifies if sensor has any listeners registered.
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.
Promise<boolean>
A promise that resolves to a boolean
denoting the availability of the sensor.
removeSubscription(subscription)
Name | Type | Description |
---|---|---|
subscription | EventSubscription | A subscription to remove. |
Removes the given subscription.
void
setUpdateInterval(intervalMs)
Name | Type | Description |
---|---|---|
intervalMs | number | Desired interval in milliseconds between sensor updates.
|
Set the sensor update interval.
void
PermissionResponse
An object obtained by permissions get and request functions.
PermissionResponse Properties
Name | Type | Description |
---|---|---|
canAskAgain | boolean | 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. |
expires | PermissionExpiration | Determines time when the permission expires. |
granted | boolean | A convenience boolean that indicates if the permission is granted. |
status | PermissionStatus | Determines the status of the permission. |
BarometerMeasurement
The altitude data returned from the native sensors.
Name | Type | Description |
---|---|---|
pressure | number | Measurement in hectopascals ( |
relativeAltitude (optional) | number | Only for: iOS Measurement in meters ( |
timestamp | number | Timestamp of the measurement in seconds. |
PermissionExpiration
Literal Type: multiple types
Permission expiration time. Currently, all permissions are granted permanently.
Acceptable values are: 'never'
| number
Subscription
A subscription object that allows to conveniently remove an event listener from the emitter.
Name | Type | Description |
---|---|---|
remove | () => void | Removes an event listener for which the subscription has been created. After calling this function, the listener will no longer receive any events from the emitter. |
UNDETERMINED
PermissionStatus.UNDETERMINED = "undetermined"
User hasn't granted or denied the permission yet.
OS | Units | Provider | Description |
---|---|---|---|
iOS | hPa | CMAltimeter | Altitude events reflect the change in the current altitude, not the absolute altitude. |
Android | hPa | Sensor.TYPE_PRESSURE | Monitoring air pressure changes. |
Web | This sensor is not available on the web and cannot be accessed. An UnavailabilityError will be thrown if you attempt to get data. |