如何在使用权限对应的功能时，以同步告知的方式向用户明示权限使用目的

import abilityAccessCtrl, { PermissionRequestResult } from '@ohos.abilityAccessCtrl' 
import bundleManager from '@ohos.bundle.bundleManager'; 
import { TAG } from '../../entryability/EntryAbility'; 
 
const context = getContext(this) 
const atManager: abilityAccessCtrl.AtManager = abilityAccessCtrl.createAtManager(); 
const permission = 'ohos.permission.ACCESS_BLUETOOTH' 
const bundleFlags = bundleManager.BundleFlag.GET_BUNDLE_INFO_WITH_APPLICATION | bundleManager.BundleFlag.GET_BUNDLE_INFO_WITH_METADATA; 
const token = bundleManager.getBundleInfoForSelfSync(bundleFlags).appInfo.accessTokenId 
 
@Entry 
@Component 
struct PermissionDialogDemo { 
  dialogController: CustomDialogController = new CustomDialogController({ 
    builder: CustomDialogExample(), 
    alignment: DialogAlignment.Top, 
    openAnimation: { 
      duration: 1000, 
      delay: 1000 
    }, 
    maskColor: '#00000000', 
    backgroundColor: '#33000000' 
  }) 
 
  build() { 
    Row() { 
      Column() { 
 
        Button('用户授权') 
          .fontSize(30) 
          .onClick((event: ClickEvent) => { 
            console.info(TAG, 'click') 
            if (atManager.checkAccessTokenSync(token, permission) === abilityAccessCtrl.GrantStatus.PERMISSION_GRANTED) { 
              console.info(TAG, '已经授权') 
            } else { 
 
              console.info(TAG, 'open') 
              this.dialogController.open() 
              console.info(TAG, 'requestPermissionsFromUser') 
              atManager.requestPermissionsFromUser(context, [permission]).then((data: PermissionRequestResult) => { 
                let grantStatus: Array<number> = data.authResults; 
                let length: number = grantStatus.length; 
                for (let i = 0; i < length; i++) { 
                  if (grantStatus[i] === 0) { 
                    // 用户授权，可以继续访问目标操作 
                    console.info(TAG, 'success') 
                  } else { 
                    // 用户拒绝授权，提示用户必须授权才能访问当前页面的功能，并引导用户到系统设置中打开相应的权限 
                    console.info(TAG, 'failed') 
                    return; 
                  } 
                } 
                this.dialogController.close() 
              }) 
            } 
          }) 
      }.width('100%') 
    }.height('100%') 
  } 
} 
 
@CustomDialog 
struct CustomDialogExample { 
  controller?: CustomDialogController 
 
  build() { 
    Column() { 
      Text('授权内容') 
        .fontSize(20) 
        .margin({ top: 10, bottom: 10 }) 
    } 
  } 
}