HarmonyOS 鸿蒙Next短时任务使用参数介绍：reason和超时

您理解的是对的，任务是在requestSuspendDelay执行后启动~

这边有一个demo，可以参考下：

index页面：
\`\`\`javascript
import { ApplicationStateChangeCallback, common } from '@kit.AbilityKit';
import SuspendTaskUtils from '../utils/SuspendTaskUtils';
import { SuspendTaskInfo } from '../viewmodel/SuspendTaskInfo';
@Entry
@Component
struct Index {
  @State message: string = '短时任务测试页面';
  private context = getContext(this) as common.UIAbilityContext;
  private messageCount: number = 0;
  aboutToAppear(): void {
    this.subscribeStateChange();
    // 启动一个定时器，每隔2s发送一条消息--模拟应用后台任务
    setInterval(() => {
      this.messageCount ++;
      console.info(`already sent ${this.messageCount} messages`);
    },2000);
  }
  /**
   * 应用前后台状态监听
   */
  subscribeStateChange(): void {
    // 1.获取ApplicationContext
    let applicationContext = this.context.getApplicationContext();
    let suspendTaskInfo: SuspendTaskInfo ;
    // 2.通过applicationContext订阅变量变化
    let appStateChangeCallBack: ApplicationStateChangeCallback = {
      onApplicationForeground() {
        console.info('app is on Foreground');
      },
      onApplicationBackground() {
        console.info('app is on Background');
        //应用由前台转为后台时，申请短时任务
        suspendTaskInfo = SuspendTaskUtils.requestSuspendDelay('test suspendtask');
        console.info(`background suspend task id:${suspendTaskInfo.id}, delayTime:${suspendTaskInfo.delayTime}`)
      }
    }
    applicationContext.on('applicationStateChange', appStateChangeCallBack);
  }
  build() {
    Row() {
      Column() {
        Text(this.message)
          .fontSize(20)
          .fontWeight(FontWeight.Bold)
          .margin({
            bottom: 10
          })
      }
      .width('100%')
    }
    .height('100%')
  }
}
\`\`\`

SuspendTaskUtils页面：
\`\`\`javascript
import { backgroundTaskManager } from '@kit.BackgroundTasksKit';
import { SuspendTaskInfo } from '../viewmodel/SuspendTaskInfo';
import { BusinessError } from '@kit.BasicServicesKit';

class SuspendTaskUtils {
  /**
   * 申请短时任务，返回任务ID和任务剩余时间
   * @param reason  申请原因
   */
  requestSuspendDelay(reason: string): SuspendTaskInfo {
    let id: number; // 申请短时任务ID
    let delayTime: number; // 本次申请短时任务的剩余时间
    let delayInfo = backgroundTaskManager.requestSuspendDelay(reason, () => {
      // 回调函数。应用申请的短时任务即将超时，通过此函数回调应用，执行一些清理和标注工作，并取消短时任务
      console.info('suspend delay task will timeout');
      backgroundTaskManager.cancelSuspendDelay(id);
    })
    id = delayInfo.requestId;
    delayTime = delayInfo.actualDelayTime;
    let taskInfo = {
      id: id,
      delayTime: delayTime
    } as SuspendTaskInfo;
    return taskInfo;
  }

  /**
   * 获取指定短时任务的剩余时间
   * @param id  待查询的短时任务ID
   */
  async getRemainingDelayTime(id: number): Promise<number> {
    let delayTime: number = -1;
    backgroundTaskManager.getRemainingDelayTime(id).then((res: number) => {
      delayTime = res;
      console.info('Succeeded in getting remaining delay time.');
    }).catch((err: BusinessError) => {
      console.error(`Failed to get remaining delay time. Code: ${err.code}, message: ${err.message}`);
    })
    return delayTime;
  }

  /**
   * 取消短时任务
   * @param id 待取消的短时任务ID
   */
   cancelSuspendDelay(id: number) {
    backgroundTaskManager.cancelSuspendDelay(id);
  }
}

let suspendTaskUtils = new SuspendTaskUtils();
export default suspendTaskUtils as SuspendTaskUtils;
\`\`\`

SuspendTaskInfo:
\`\`\`typescript
export interface SuspendTaskInfo {
  id: number ; // 短时任务ID
  delayTime: number; // 本次申请短时任务的剩余时间
}
\`\`\`