@ohos.telephony.observer (Observer) (System API)

The observer module provides event subscription management functions. You can register or unregister an observer that listens for the following events: network status change, signal status change, call status change, cellular data connection status, uplink and downlink data flow status of cellular data services, and SIM status change.

NOTE

The initial APIs of this module are supported since API version 6. Newly added APIs will be marked with a superscript to indicate their earliest API version. This topic describes only system APIs provided by the module. For details about its public APIs, see @ohos.telephony.observer (Observer).

Modules to Import

import observer from '@ohos.telephony.observer';

observer.on('cellInfoChange')⁸⁺

on(type: 'cellInfoChange', callback: Callback<Array<CellInformation>>): void

Registers an observer for cell information change events. This API uses an asynchronous callback to return the result.

System API: This is a system API.

Required permissions: ohos.permission.LOCATION and ohos.permission.APPROXIMATELY_LOCATION

System capability: SystemCapability.Telephony.StateRegistry

Parameters

Error codes

For details about the error codes, seeohos.telephony (Telephony) Error Codes.

Example

import radio from '@ohos.telephony.radio';

observer.on('cellInfoChange', (data: Array<radio.CellInformation>) => {
    console.log("on cellInfoChange, data:" + JSON.stringify(data));
});

observer.on('cellInfoChange')⁸⁺

on(type: 'cellInfoChange', options: ObserverOptions, callback: Callback<Array<CellInformation>>): void

Registers an observer for signal status change events of the SIM card in the specified slot. This API uses an asynchronous callback to return the execution result.

System API: This is a system API.

Required permissions: ohos.permission.LOCATION and ohos.permission.APPROXIMATELY_LOCATION

System capability: SystemCapability.Telephony.StateRegistry

Parameters

Error codes

For details about the error codes, seeohos.telephony (Telephony) Error Codes.

Example

import radio from '@ohos.telephony.radio';

let options: observer.ObserverOptions = {
    slotId: 0
}
observer.on('cellInfoChange', options, (data: Array<radio.CellInformation>) => {
    console.log("on cellInfoChange, data:" + JSON.stringify(data));
});

observer.off('cellInfoChange')⁸⁺

off(type: 'cellInfoChange', callback?: Callback<Array<CellInformation>>): void

Unregisters the observer for cell information change events. This API uses an asynchronous callback to return the result.

NOTE

You can pass the callback of the on function if you want to cancel listening for a certain type of event. If you do not pass the callback, you will cancel listening for all events.

System API: This is a system API.

System capability: SystemCapability.Telephony.StateRegistry

Parameters

Error codes

For details about the error codes, seeohos.telephony (Telephony) Error Codes.

Example

import radio from '@ohos.telephony.radio';

let callback: (data: Array<radio.CellInformation>) => void = (data: Array<radio.CellInformation>) => {
    console.log("on cellInfoChange, data:" + JSON.stringify(data));
}
observer.on('cellInfoChange', callback);
// You can pass the callback of the on method to cancel listening for a certain type of callback. If you do not pass the callback, you will cancel listening for all callbacks.
observer.off('cellInfoChange', callback);
observer.off('cellInfoChange');