harmony 鸿蒙Unsubscribing from Common Events in Dynamic Mode

2025-06-06
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Unsubscribing from Common Events in Dynamic Mode

When to Use

After a service is finished in the dynamic mode, the subscriber should proactively unsubscribe from the event. You can call unsubscribe() to unsubscribe from a common event that is no longer required.

Available APIs

API	Description
unsubscribe(subscriber: CommonEventSubscriber, callback?: AsyncCallback)	Unsubscribes from a common event.

How to Develop

Import the commonEventManager module.

   import { BusinessError, commonEventManager } from '@kit.BasicServicesKit';
   import { hilog } from '@kit.PerformanceAnalysisKit';

   const TAG: string = 'ProcessModel';
   const DOMAIN_NUMBER: number = 0xFF00;

Subscribe to an event by following the procedure described in Subscribing to Common Events in Dynamic Mode.
Call unsubscribe() in CommonEvent to unsubscribe from an event.

   // The subscriber object is created during event subscription.
   if (subscriber !== null) {
     commonEventManager.unsubscribe(subscriber, (err: BusinessError) => {
       if (err) {
         hilog.error(DOMAIN_NUMBER, TAG, `UnsubscribeCallBack err = ${JSON.stringify(err)}`);
       } else {
         hilog.info(DOMAIN_NUMBER, TAG, `Unsubscribe success`);
         subscriber = null;
       }
     })
   }