HarmonyOS 鸿蒙Next NFC tag.getTagInfo(want) 一直等于null

HarmonyOS 鸿蒙Next NFC tag.getTagInfo(want) 一直等于null

onCreate(want, launchParam) {
    let AtManager = abilityAccessCtrl.createAtManager();
    AtManager.requestPermissionsFromUser(this.context, permissions).then((data) => {
      hilog.info(0x0000, 'testTag', '%{public}s', 'request permissions from user success' + data);
    }).catch((err) => {
      hilog.error(0x0000, 'testTag', 'Failed to request permissions from user. Cause: %{public}s', JSON.stringify(err) ?? '');
    });
    hilog.info(0x0000, 'testTag', '%{public}s', 'Ability onCreate');


    var tagInfo;
    var isNDEFTag = false;
    var ndefTag;

    try {
      tagInfo = tag.getTagInfo(want);

      if (tagInfo == null || tagInfo == undefined) {
        console.log("no TagInfo to be created, ignore it.");
      }else {
        // get the supported technologies for this found tag.
        for (var i = 0; i < tagInfo.technology.length; i++) {
          if (tagInfo.technology[i] == tag.NDEF) {
            isNDEFTag = true;
          }
          // also check for technology: tag.NFC_B/NFC_F/NFC_V/NDEF/MIFARE_CLASSIC/MIFARE_ULTRALIGHT/NDEF_FORMATABLE
        }

        // use NfcA APIs to access the found tag.
        if (isNDEFTag) {
          try {
            ndefTag = tag.getNdef(tagInfo);
          } catch (error) {
            console.log("tag.getNfcATag catched error: " + error);
          }
          // other code to read or write this found tag.

          if (!ndefTag.isTagConnected()) {
            if (!ndefTag.connectTag()) {
              console.log("ndefTag connectTag failed.");
            } else {
              // try {
              //   ndefTag.readNdef().then((ndefmessage) => {
              //     console.log("ndef readNdef Promise ndefmessage: " + ndefmessage);
              //   }).catch((err) => {
              //     console.log("ndef readNdef Promise err: " + err);
              //   });
              // } catch (busiError) {
              //   console.log("ndef readNdef Promise catched busiError: " + busiError);
              // }

              try {
                ndefTag.writeNdef(ndefMessage).then(() => {
                  console.log("ndef writeNdef Promise success.");
                }).catch((err)=> {
                  console.log("ndef writeNdef err: " + err);
                });
              } catch (busiError) {
                console.log("ndef writeNdef Promise catch busiError: " + busiError);
              }
            }
          }
        }
      }
    } catch (error) {
      console.log("tag.getTagInfo catched error: " + error);
    }
  }