Iconbutton color doesn't change: - flutter

Question

i need help. When I press Iconbutton the document is added (or deleted from) to Firestore , but the color of the Iconbutton doesn't change.
class DisplaydataScreen extends StatefulWidget {
const DisplaydataScreen({Key key}) : super(key: key);
#override
_DisplaydataScreenState createState() => _DisplaydataScreenState();
}
class _DisplaydataScreenState extends State<DisplaydataScreen> {
String userID = "";
var Data;
Icon favicon = Icon(
LineIcons.heart,
size: 20,
);
#override
void initState() {
super.initState();
fetchUserInfo();
}
fetchUserInfo() {
User getUser = FirebaseAuth.instance.currentUser;
userID = getUser.uid;
print(userID);
}
Future<List<Tweet>> getTweetFromJSON(
BuildContext context, String topic) async {
String jsonString =
await DefaultAssetBundle.of(context).loadString('tweets.json');
List<dynamic> raw = jsonDecode(jsonString);
return raw.map((e) => Tweet.fromJSon(e)).toList();
}
#override
Widget build(BuildContext context) {
final args = ModalRoute.of(context).settings.arguments;
return Scaffold(
body: Container(
child: FutureBuilder(
future: getTweetFromJSON(context, args),
builder: (context, data) {
List<Tweet> posts = data.data;
return ListView.builder(
itemCount: posts.length,
itemBuilder: (context, index) {
return ListTile(
title: Text(
posts[index].name,
style:
TextStyle(fontSize: 15.0, fontWeight: FontWeight.bold),
),
subtitle: Text(posts[index].tweet),
// IconButton
trailing: IconButton(
onPressed: () async {
final userDocRef = favorite.doc(
posts[index].name,
);
final doc = await userDocRef.get();
if (!doc.exists) {
setState(() {
favicon = Icon(LineIcons.heart,
color: Colors.white, size: 20);
});
addfavorite(
posts[index].name,
posts[index].photos,
);
} else {
setState(() {
favicon = Icon(LineIcons.heart,
color: Colors.red, size: 20);
});
deletefavorite(posts[index].name);
}
},
icon: favicon,
),
);
},
);
},
),
),
);
}
This is the add and delete methode:
final CollectionReference favorite =
FirebaseFirestore.instance.collection('favorite');
Future<void> addfavorite(String name, List photos) async {
return await favorite.doc(name).set({
'name': name,
'photos': photos,
});
}
Future<void> deletefavorite( name) async {
await favorite.doc(name).delete();
}
This is a Screenshot of my project, what i want is that the iconbutton remain colored as long as they are favorites after being pressed

Answer 1

This should work:
import 'package:flutter/material.dart';
class DisplaydataScreen extends StatefulWidget {
const DisplaydataScreen({Key key}) : super(key: key);
#override
_DisplaydataScreenState createState() => _DisplaydataScreenState();
}
class _DisplaydataScreenState extends State<DisplaydataScreen> {
String userID = "";
var Data;
#override
void initState() {
super.initState();
fetchUserInfo();
}
fetchUserInfo() {
User getUser = FirebaseAuth.instance.currentUser;
userID = getUser.uid;
print(userID);
}
Future<List<Tweet>> getTweetFromJSON(BuildContext context,
String topic) async {
String jsonString =
await DefaultAssetBundle.of(context).loadString('tweets.json');
List<dynamic> raw = jsonDecode(jsonString);
return raw.map((e) => Tweet.fromJSon(e)).toList();
}
#override
Widget build(BuildContext context) {
final args = ModalRoute
.of(context)
.settings
.arguments;
return Scaffold(
body: Container(
child: FutureBuilder(
future: getTweetFromJSON(context, args),
builder: (context, data) {
List<Tweet> posts = data.data;
return ListView.builder(
itemCount: posts.length,
itemBuilder: (context, index) {
return FavoriteListTileItem(post: posts[index],);
},
);
},
),
),
);
}
}
class FavoriteListTileItem extends StatefulWidget {
final Tweet post;
const FavoriteListTileItem({Key? key, this.post}) : super(key: key);
#override
State<FavoriteListTileItem> createState() => _FavoriteListTileItemState();
}
class _FavoriteListTileItemState extends State<FavoriteListTileItem> {
Icon favicon = Icon(
LineIcons.heart,
size: 20,
);
#override
Widget build(BuildContext context) {
return ListTile(
title: Text(
widget.post.name,
style:
TextStyle(fontSize: 15.0, fontWeight: FontWeight.bold),
),
subtitle: Text(widget.post.tweet),
// IconButton
trailing: IconButton(
onPressed: () async {
final userDocRef = favorite.doc(
widget.post.name,
);
final doc = await userDocRef.get();
if (!doc.exists) {
setState(() {
favicon = Icon(LineIcons.heart,
color: Colors.white, size: 20);
});
addfavorite(
widget.post.name,
widget.post.photos,
);
} else {
setState(() {
favicon = Icon(LineIcons.heart,
color: Colors.red, size: 20);
});
deletefavorite(widget.post.name);
}
},
icon: favicon,
),
);
}
}