How do I add loading screen in Flutter - flutter

Question

I am making an app with flutter and I want a loading screen while fetching data from firestore I used to do this in android by setvisibilty .I am new to flutter and I don't know how to do it I saw some questions on stack but they didn't seem to help full
I want to show the loading screen if firebaseUser is not null,
this is my initState method
void initState() {
super.initState();
isRegistered();
}
#override
Widget build(BuildContext context) {
return Scaffold(
body: Container(
padding: EdgeInsets.all(32),
child: Form(
child: Column(
crossAxisAlignment: CrossAxisAlignment.start,
mainAxisAlignment: MainAxisAlignment.center,
children: <Widget>[
Text("Login"),
SizedBox(
height: 16,
),
Row(
mainAxisAlignment: MainAxisAlignment.spaceAround,
children: <Widget>[
Container(
width: 50,
child: TextFormField(
maxLength: 4,
keyboardType: TextInputType.number,
controller: countryCodeController,
decoration: InputDecoration(
hintText: '+251',
),
),
),
Container(
width: 200,
child: TextFormField(
maxLength: 9,
keyboardType: TextInputType.number,
controller: phonenumberController,
decoration: InputDecoration(
hintText: '912345678',
),
),
),
],
),
SizedBox(
height: 16,
),
Container(
width: double.infinity,
child: FlatButton(
child: Text('Login'),
color: Colors.white,
padding: EdgeInsets.all(16),
onPressed: () {
final phoneNumber = countryCodeController.text.trim() + phonenumberController.text.trim();
if(phonenumberController.text.trim().length == 9 || countryCodeController.text.trim().length == 4){
loginUser(phoneNumber, context);
}else{
Fluttertoast.showToast(msg: "wronge input");
}
}),
)
],
),
),
),
);
}
void isRegistered() async{
FirebaseAuth firebaseAuth = FirebaseAuth.instance;
final FirebaseUser firebaseUser = await firebaseAuth.currentUser();
final snapShot = await Firestore.instance.collection("users").document(
firebaseUser.uid).get();
if (firebaseUser != null) {
if (snapShot.exists) {
Navigator.pushReplacement(
context,
MaterialPageRoute(
builder: (context) => HomePage(
firebaseUser: firebaseUser,
)));
}else{
}
}
}
}

Answer 1

Just check out this example I have created for you:
class MyApp extends StatefulWidget {
#override
_MyAppState createState() => _MyAppState();
}
class _MyAppState extends State<MyApp> {
bool _isLoading = false; // This is initially false where no loading state
List<Timings> timingsList = List();
#override
void initState() {
super.initState();
dataLoadFunction(); // this function gets called
}
dataLoadFunction() async {
setState(() {
_isLoading = true; // your loader has started to load
});
// fetch you data over here
setState(() {
_isLoading = false; // your loder will stop to finish after the data fetch
});
}
#override
Widget build(BuildContext context) {
return MaterialApp(
home: Scaffold(
body: _isLoading
? CircularProgressIndicator() // this will show when loading is true
: Text('You widget tree after loading ...') // this will show when loading is false
),
);
}
}
Let me know if it works

Answer 2

I use flutter_spinkit for the animation.
The package flutter_spinkit is a collection of loading indicators animated with flutter.
Here the Loading widget:
import 'package:flutter/material.dart';
import 'package:flutter_spinkit/flutter_spinkit.dart';
class Loading extends StatelessWidget {
#override
Widget build(BuildContext context) {
return Container(
color: Colors.white,
child: Center(
child: SpinKitFadingCube(
color: Colors.lightGreen[100],
size: 50.0
)
)
);
}
}
Then, from within your widgets, you need to:
import '[yourpath]/loading.dart';
bool loading = false;
#override
Widget build(BuildContext context) {
return loading ? Loading() : Scaffold(
body: Container(...
Wherever is your click event, you should set the state of loading to TRUE:
setState(() => loading = true)
and where the callback is, you should set the state back to FALSE:
setState(() => loading = false)

Answer 3

You can try creating a widget component such as this and save it with the name progress.dart
import 'package:flutter/material.dart';
Container circularProgress() {
return Container(
alignment: Alignment.center,
padding: EdgeInsets.only(top: 10.0),
child: CircularProgressIndicator(
strokeWidth: 2.0,
valueColor: AlwaysStoppedAnimation(primaryColor), //any color you want
),
);
}
Then import the progress.dart and create a separate container
Container loadingScreen() {
return circularProgress();
}
Then change your code to:
class RootScreenSM extends StatefulWidget {
#override
_RootScreenSMState createState() => _RootScreenSMState();
}
class _RootScreenSMState extends State<RootScreenSM> {
#override
Widget build(BuildContext context) {
return StreamBuilder<FirebaseUser>(
stream: FirebaseAuth.instance.onAuthStateChanged,
builder: (BuildContext context, snapshot) {
if (snapshot.connectionState == ConnectionState.waiting) {
return loadingScreen(); // Container that you just created
} else {
if (snapshot.hasData) {
return HomePage(
firebaseUser: snapshot.data,
);
} else {
return
notloggedin();
}
}
},
);
}
You can try this method and let us know if it worked

Answer 4

You can do something like this
class RootScreenSM extends StatefulWidget {
#override
_RootScreenSMState createState() => _RootScreenSMState();
}
class _RootScreenSMState extends State<RootScreenSM> {
#override
Widget build(BuildContext context) {
return StreamBuilder<FirebaseUser>(
stream: FirebaseAuth.instance.onAuthStateChanged,
builder: (BuildContext context, snapshot) {
if (snapshot.connectionState == ConnectionState.waiting) {
return new Container(
color: Colors.white,
//customize container look and feel here
);
} else {
if (snapshot.hasData) {
return HomePage(
firebaseUser: snapshot.data,
);
} else {
return
notloggedin();
}
}
},
);
}