您可以进入设置> [AppName]，各种权限会显示在那里，您可以在那里切换它们。

尝试使用包下面的代码 permission_handler 来管理权限。

@override
void initState() {
  super.initState();
  checkPermission();
}

Future<void> getImage() async {
  PermissionStatus status = await Permission.photos.status;
  if (status.isGranted) {
    // Proceed to pick an image
  } else {
    await requestPermission();
  }
}

使用以下方法检查权限的当前状态。

Future<void> checkPermission() async {
  PermissionStatus status = await Permission.photos.status;

  if (status.isDenied) {
    // Permission is denied, show a dialog or message to the user
  } else if (status.isGranted) {
    // Permission is granted, proceed with accessing images
  }
}

如果权限被拒绝，则显示一个对话框，解释为什么需要该权限以及如何启用它。

void showPermissionDialog(BuildContext context) {
  showDialog(
    context: context,
    builder: (BuildContext context) {
      return AlertDialog(
        title: Text('Permission Required'),
        content: Text('This app needs permission to access your photos. Please enable it in settings.'),
        actions: <Widget>[
          TextButton(
            child: Text('Open Settings'),
            onPressed: () {
              openAppSettings();
            },
          ),
          TextButton(
            child: Text('Cancel'),
            onPressed: () {
              Navigator.of(context).pop();
            },
          ),
        ],
      );
    },
  );

如果用户最初拒绝该权限但尚未永久拒绝，则可以使用以下方法再次请求该权限。

Future<void> requestPermission() async {
  PermissionStatus status = await Permission.photos.request();

  if (status.isGranted) {
    // Permission granted, proceed with accessing images
  } else if (status.isDenied) {
    // Permission still denied, show a dialog
    showPermissionDialog(context);
  } else if (status.isPermanentlyDenied) {
    // Permission is permanently denied
    showPermissionDialog(context);
  }
}