Search Result does not update instantly flutter - flutter

Question

I'm emulating this search and filter github here and the codes are almost the same but the filtered results do not update instantly while I type and also I faced the following issues:
I will have to press enter on my laptop to finally get the filtered list
When I hit the close icon(which is to clear all the words), I will have to tap the searchbar again so that all my listtile are back on the listview.
Here's my code:
class _CurrencySelectState extends State<CurrencySelect> {
late List<Currency> resCur;
String query = '';
#override
void initState() {
super.initState();
resCur = currencyList;
}
void searchCur(String query) {
final List<Currency> filteredCur = currencyList.where((cur) {
final symbolLower = cur.symbol.toLowerCase(); // Search using symbol
final nameLower = cur.country.toLowerCase(); // Search using country
final searchLower = query.toLowerCase();
return symbolLower.contains(searchLower) ||
nameLower.contains(searchLower);
}).toList();
setState(() {
this.query = query;
resCur = filteredCur;
});
}
#override
Widget build(BuildContext context) {
Widget buildCur(Currency cur) => ListTile(
leading: Padding(
padding: EdgeInset.all(5)
child: SizedBox(
child: Column(
children: <Widget>[
SvgPicture.asset(
cur.assetPath,
),
]),
),
),
title: Column(
children: [
Text(
cur.symbol,
style: TextStyle(
...
),
Text(
cur.name,
style: TextStyle(
...
),
],
),
trailing: Text(
"0.25",
style: TextStyle(
...
),
);
return TextButton(
onPressed: () async {
showModalBottomSheet(
enableDrag: false,
context: context,
isScrollControlled: true,
builder: (BuildContext context) {
return DraggableScrollableSheet(
expand: false,
builder: (context, scrollController) {
return Column(
children: <Widget>[
SearchWidget(
text: query,
onChanged: searchCur,
hintText: "Enter symbol or country"
),
Expanded(
child: ListView.builder(
controller: scrollController,
itemCount: resCur.length,
itemBuilder: (context, int index) {
final cur = resCur[index];
return buildCur(cur);
},
),
)
],
);
},
);
});
},
child: Row(
mainAxisAlignment: MainAxisAlignment.spaceAround,
children: [
Text(
...
),
SvgPicture.asset(
...
)
],
));
}
}
Searchwidget code:
import 'package:flutter/material.dart';
class SearchWidget extends StatefulWidget {
final String text;
final ValueChanged<String> onChanged;
final String hintText;
const SearchWidget({
Key? key,
required this.text,
required this.onChanged,
required this.hintText,
}) : super(key: key);
#override
_SearchWidgetState createState() => _SearchWidgetState();
}
class _SearchWidgetState extends State<SearchWidget> {
final controller = TextEditingController();
#override
Widget build(BuildContext context) {
final styleActive = TextStyle(color: Colors.black);
final styleHint = TextStyle(color: Colors.black54);
final style = widget.text.isEmpty ? styleHint : styleActive;
return Container(
height: 42,
margin: const EdgeInsets.fromLTRB(16, 16, 16, 16),
decoration: BoxDecoration(
borderRadius: BorderRadius.circular(12),
color: Colors.white,
border: Border.all(color: Colors.black26),
),
padding: const EdgeInsets.symmetric(horizontal: 8),
child: TextField(
controller: controller,
decoration: InputDecoration(
icon: Icon(Icons.search, color: style.color),
suffixIcon: widget.text.isNotEmpty
? GestureDetector(
child: Icon(Icons.close, color: style.color),
onTap: () {
controller.clear();
widget.onChanged('');
FocusScope.of(context).requestFocus(FocusNode());
},
)
: null,
hintText: widget.hintText,
hintStyle: style,
border: InputBorder.none,
),
style: style,
onChanged: widget.onChanged,
),
);
}
}