Github App - Final

import 'dart:convert';
import 'package:flutter/material.dart';
import 'package:githubapp/user.dart';
import 'package:url_launcher/url_launcher.dart';
import 'service.dart';

class HomePage extends StatefulWidget {
  @override
  _HomePageState createState() => _HomePageState();
}

class _HomePageState extends State<HomePage> {
  APIService apiService = APIService();

  bool isLoading = true;
  List<User> users;

  @override
  void initState() {
    super.initState();
    fetchGithubUsersList();
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      backgroundColor: Colors.white,
      appBar: AppBar(
        title: Text(
          'Github Users',
          style: TextStyle(color: Colors.white, fontSize: 14),
        ),
        centerTitle: false,
        backgroundColor: Colors.black87,
      ),
      body: isLoading
          ? Center(
              child: Container(
                margin: EdgeInsets.symmetric(vertical: 20),
                alignment: Alignment.center,
                child: SizedBox(
                  child: CircularProgressIndicator(
                    valueColor: new AlwaysStoppedAnimation<Color>(Colors.black),
                    strokeWidth: 3.0,
                  ),
                  height: 40,
                  width: 40,
                ),
              ),
            )
          : ListView.separated(
              itemBuilder: (context, index) => userTile(
                  users[index].login,
                  users[index].avatarUrl,
                  users[index].type,
                  users[index].htmlUrl),
              separatorBuilder: (context, index) => Divider(
                height: 1,
              ),
              itemCount: users.length,
              shrinkWrap: true,
            ),
    );
  }

  Widget userTile(
      String fullName, String avatarUrl, String location, String pageUrl) {
    return ListTile(
      leading: Container(
        height: 50,
        width: 50,
        decoration: BoxDecoration(
            color: Colors.black87,
            borderRadius: BorderRadius.all(Radius.circular(25))),
        child: ClipRRect(
          borderRadius: BorderRadius.circular(25),
          child: Image.network(
            //'https://picsum.photos/250?image=9',
            avatarUrl,
            fit: BoxFit.contain,
          ),
        ),
      ),
      title: Text(
        '$fullName',
        style: TextStyle(
            color: Colors.black87, fontSize: 15, fontWeight: FontWeight.w500),
      ),
      subtitle: Text(
        '$location',
        style: TextStyle(
            color: Colors.grey, fontSize: 12, fontWeight: FontWeight.w300),
      ),
      trailing: GestureDetector(
        //onTap: () => _launchURL('https://github.com/'),
        onTap: () => _launchURL(pageUrl),
        child: Container(
          height: 25,
          width: 80,
          decoration: BoxDecoration(
              border: Border.all(color: Colors.black, width: 1.5),
              borderRadius: BorderRadius.all(Radius.circular(22))),
          padding: EdgeInsets.all(3),
          child: Row(
            crossAxisAlignment: CrossAxisAlignment.center,
            mainAxisAlignment: MainAxisAlignment.center,
            children: <Widget>[
              Text(
                'View Profile',
                style: TextStyle(
                    color: Colors.black87,
                    fontSize: 8,
                    fontWeight: FontWeight.w400),
              ),
              Image.asset(
                'assets/images/github.png',
                width: 20,
                height: 20,
              ),
            ],
          ),
        ),
      ),
    );
  }

  _launchURL(String url) async {
    if (await canLaunch(url)) {
      await launch(url);
    } else {
      throw 'Could not launch $url';
    }
  }

  fetchGithubUsersList() async {
    setState(() {
      isLoading = true;
    });

    var usersResponse = apiService.getUsers();
    usersResponse.then((response) {
      if (response.statusCode == 200) {
        var decodedJson = json.decode(response.body);
        debugPrint(decodedJson.toString());
        setState(() {
          isLoading = false;
          users = UsersModel.fromJson(decodedJson).usersList;
          debugPrint('Users list size: ${users.length}');
        });
      } else {
        setState(() {
          isLoading = false;
        });

        showDialog(
            context: context,
            builder: (BuildContext context) {
              return AlertDialog(
                title: Text("Error"),
                content: Text('Could not retrieve data'),
                actions: [
                  FlatButton(
                    child: Text("Ok"),
                    onPressed: () {
                      Navigator.of(context).pop();
                    },
                  )
                ],
              );
            });
      }
    }).catchError((onError) {
      print(onError);
      showDialog(
          context: context,
          builder: (BuildContext context) {
            return AlertDialog(
              title: Text("Error"),
              content: Text('${onError.toString()}'),
              actions: [
                FlatButton(
                  child: Text("Ok"),
                  onPressed: () {
                    Navigator.of(context).pop();
                  },
                )
              ],
            );
          });
    });
  }
}

thanks sir