颤抖-权限请求道具不显示

Question

我正在使用此Permission_handler软件包来使用存储权限。我想检查用户是否已经授予了权限，如果没有，我想向用户显示提示询问权限的提示。这是我的代码：

void checkPer() async {
    PermissionStatus permission = await PermissionHandler()
        .checkPermissionStatus(PermissionGroup.storage);

    if (permission != PermissionStatus.granted ||
        permission != PermissionStatus.restricted) {
      Map<PermissionGroup, PermissionStatus> permissions =
          await PermissionHandler()
              .requestPermissions([PermissionGroup.storage]);
      //print("permission request result is " + resReq.toString());
      if (permissions[PermissionGroup.storage] == PermissionStatus.granted ||
          permissions[PermissionGroup.storage] == PermissionStatus.restricted) {
        // await downloadFile();
      }
    } else {
      // await downloadFile();
    }
  }

问题是没有显示提示。有什么想法吗？