How to preload network images from fireabse storage in flutter with dart?

Question

I have a problem to display user images immediately...

I have the image URLs of the users stored in cloud firestore. I have a model where I get the URLs and store them in a list. The users are also in a list.

All images are saved in firebase storage.

So now to my problem: I want that all images of the user, each user have at least 3 images, are show immediately when the app has loaded all data. So when I open the app a loading animation is showing and than the layout is showing.

How can I achieve this?

I also tried already this method but it doesn't work. It shows me this error message:

The following StateError was thrown image failed to precache: Bad state: Failed to load "url"

This is the class CacheUserImages

import 'package:flutter/material.dart';
import 'package:flutter_advanced_networkimage_2/provider.dart';

class CacheUserImages {
 static Future cacheUserImages(
      BuildContext _cacheUserImagesContext, String cacheUserImagesUrl) =>
  precacheImage(
      AdvancedNetworkImage(
        cacheUserImagesUrl,
        useDiskCache: true,
        cacheRule: CacheRule(
          maxAge: const Duration(days: 7),
        ),
      ),
      _cacheUserImagesContext);
}

This is inside main and I call _getUser inside initState

Future _getUser(
  BuildContext _getUserContext, List<UserModel> _getUserUser) async {
_getUserUser
    .map((_user) => _getUserImages(_getUserContext, _user))
    .toList();
}

Future _getUserImages(
  BuildContext _getUserImagesContext, UserModel _getUserImagesUser) async {
await Future.wait(_getUserImagesUser.userImages
    .map((_userImages) =>
        CacheUserImages.cacheUserImages(_getUserImagesContext, _userImages))
    .toList());

setState(() {
  _loadingAppData = false;
});
}

It would be very helpfull if someone could show me a full example of how to precache images before the UI builds and than show the precached images immediately without an extra loading animation like in CachedNetworkImage.