How to Upload & Download Images from Fire Base Using Flutter

import 'dart:io';
import 'package:firebase_storage/firebase_storage.dart'; // For File Upload To Firestore
import 'package:flutter/material.dart';
import 'package:image_picker/image_picker.dart'; // For Image Picker
import 'package:path/path.dart' as Path;

void main() {
  runApp(MyApp());
}

class MyApp extends StatelessWidget {
  // This widget is the root of your application.
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      title: 'WallPaper Demo',
      theme: ThemeData(
        // This is the theme of your application.
        //
        // Try running your application with "flutter run". You'll see the
        // application has a blue toolbar. Then, without quitting the app, try
        // changing the primarySwatch below to Colors.green and then invoke
        // "hot reload" (press "r" in the console where you ran "flutter run",
        // or simply save your changes to "hot reload" in a Flutter IDE).
        // Notice that the counter didn't reset back to zero; the application
        // is not restarted.
        primarySwatch: Colors.blue,
        // This makes the visual density adapt to the platform that you run
        // the app on. For desktop platforms, the controls will be smaller and
        // closer together (more dense) than on mobile platforms.
        visualDensity: VisualDensity.adaptivePlatformDensity,
      ),
      home: MyHomePage(),
    );
  }
}

class MyHomePage extends StatefulWidget {
  @override
  _MyHomePageState createState() => _MyHomePageState();
}

class _MyHomePageState extends State<MyHomePage> {
  File _image;
  String _uploadedFileURL;

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: Text('Firestore File Upload'),
      ),
      body: Center(
        child: Column(
          children: <Widget>[
            Text('Selected Image'),
            _image != null
                ? Image.asset(
                    _image.path,
                    height: 150,
                  )
                : Container(height: 150),
            _image == null
                ? RaisedButton(
                    child: Text('Choose File'),
                    onPressed: chooseFile,
                    color: Colors.cyan,
                  )
                : Container(),
            _image != null
                ? RaisedButton(
                    child: Text('Upload File'),
                    onPressed: uploadFile,
                    color: Colors.cyan,
                  )
                : Container(),
            _image != null
                ? RaisedButton(
                    child: Text('Clear Selection'),
                    // onPressed: clearSelection,
                  )
                : Container(),
            Text('Uploaded Image'),
            _uploadedFileURL != null
                ? Image.network(
                    _uploadedFileURL,
                    height: 150,
                  )
                : Container(),
          ],
        ),
      ),
    );
  }

  Future chooseFile() async {
    await ImagePicker.pickImage(source: ImageSource.gallery).then((image) {
      setState(() {
        _image = image;
      });
    });
  }

  Future uploadFile() async {
    StorageReference storageReference = FirebaseStorage.instance
        .ref()
        .child('chats/${Path.basename(_image.path)}}');
    StorageUploadTask uploadTask = storageReference.putFile(_image);
    await uploadTask.onComplete;
    print('File Uploaded');
    storageReference.getDownloadURL().then((fileURL) {
      setState(() {
        _uploadedFileURL = fileURL;
      });
    });
  }
}