Some Background

My experience with developing mobile apps was very limited. To be honest, I had tried doing something basic with PhoneGap long back and developed few Hello World style applications with Android SDK. But nothing with an incremental success to make it like a useful app.

I had built my own apprehensions about the complexity in setting up things, building, deploying etc. This caused huge reluctance in me in trying out mobile app development (sigh) in past.

Recently I learnt about Flutter from Google. What caught my attention was,

Flutter - Beautiful native apps in record time

I felt, this statement is so true. Here I present my experience in building a Near Realistic, (almost) Beautiful native app developed in around 9 hours(record time, not continuous though.)!

I will consider this as record time because, I never had any experience working with,

• Dart as a Programming Language and it's APIs. I had to learn, understand the useful APIs and code.
• Building anything that has to do with Native app.
• Setup => Develop => Publish cycle of a Mobile App.

This post is all about sharing the joy of Developing a native app using Flutter. I am sure, you will enjoy as well if you are a beginner like me with it.

What's the App about?

I didn't want to build a Hello World again. I intended to learn the followings within a quick time by doing good amount of hands-on:

• Know all about the Setup without getting demotivated.
• Write good code.
• Routing and Navigation, Complex?
• Layout and Design, Do I need to be a designer?
• Play with Images and Styles, must be easy!
• Server Communication with API Call, Hmmm....
• Handling Custom Images/Icons
• Packaging and building
• Installation of the app
• Publishing it on Play Store, the fun begins.

I had enjoyed lots while developing a Prediction app using node-cli before. How about building a Prediction mobile app? Here is how the interaction goes:

Let us go Step by Step

Here is all that I could gather as my learning from it:

Setting up the environment

I have used Windows 10 operating system and the aim was to develop, test the APP on an Android device. However I ended up testing it on an IOS phone as well without changing any of the source code.

To set up the environment, I just followed this: Flutter Install Doc. Follow it just line by line. All will be set, guaranteed.

Note: if you are not using Google Nexus phone, you may feel that, you got to use additional driver for your OS to connect to the phone using USB for debugging. You do not need to do anything additional.

Setting up the Editor to code and debug

I have configured VS Code as my editor for coding and debugging. Here is the link that I followed to set it up: Flutter VS Code setup

Flutter Doctor

Keep running flutter doctor command to ensure, you are on right track.

Code Structure

Dart is the language behind Flutter. In many of the examples out there, you will see one main.dart file contains tons of code. As the application grows, this file becomes unmanageable. To make sure, I do not fall into this trap, I had structured my code as below:

The main.dart file would look like:

import 'package:flutter/material.dart';

import 'pages/homePage.dart';
import 'pages/resultPage.dart';


void main() => runApp(new PredictionApp());

class PredictionApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return new MaterialApp(
      title: 'Prediction',
      theme: new ThemeData(
        primarySwatch: Colors.red,
      ),
      home: new HomePage(title: 'Prediction'),
       routes: <String, WidgetBuilder> {
        '/home': (BuildContext context) => new HomePage(),
        '/result' : (BuildContext context) => new ResultPage()
      },
    );
  }
}

Routing

The Prediction app is a multi-page app. The Home Page asks for information from users. The Result Page fetches the information and show that to the users. There is also an option to go back to the Home Page. Well, we need Routing.

These lines in main.dart file do the trick:

routes: <String, WidgetBuilder> {
        '/home': (BuildContext context) => new HomePage(),
        '/result' : (BuildContext context) => new ResultPage()
}

Layout, Images and Style

The Prediction app has multiple Widgets in use. Like, the title bar at the top, Body for the content, Form which helps collecting info from users, Button, Images, Texts etc. So following leanings are essential:

• Introduction to Widgets
• Introduction to Layout
• Learn Interactivity

These links are super important and very informative, engaging to follow.

Server communication

Flutter uses plug-in based approach. We do not get everything installed by default with the framework itself. Rather, we need to install what we need and import into the dart file to make use of it. The Prediction app needs to interact with the Horoscope-API that exposes HTTP methods to fetch data. The response format of the API calls are JSON.

To support this, I had added following dependency in pubspec.yaml file:

http: ^0.12.0+2

and in main.dart file, imported it along with the json parser provided by Dart language itself.

import 'package:http/http.dart' as http;
import 'dart:convert';

These three lines Request the API, Receive JSON response and Parse it respectively:

final response = await http.get('http://horoscope-api.herokuapp.com/horoscope/' + predictionData.getDuration().toLowerCase() + '/' + zodiacSign);
final responseJson = json.decode(response.body); 
Horoscope horoscope = new Horoscope.fromJson(responseJson); 

The last line of the code parse the response JSON to map the value to the model(Horoscope) attributes.

The Horoscope model class is as simple as this:

class Horoscope {
  String horoscope;
  String sunsign;

  Horoscope({this.horoscope,this.sunsign});


  factory Horoscope.fromJson(Map<String, dynamic> parsedHoroscope){
      return Horoscope(
        horoscope: parsedHoroscope['horoscope'],
        sunsign : parsedHoroscope['sunsign']
      );
  }
}

Handling Custom Images

I have used many Custom Images(icons mostly) to represent various Zodiac Signs. Including the Custom Images and Icons are very easy.

• Create a folder called assets at the same level of the pubspec.yaml file.
• Keep all your icons and images inside the assets folder.
• Add the following entry into the pubspec.yaml file to include all the icons and images from asset folder:

assets:
    - assets/

If you want to include selected icons/images, please specify the names respectively.

Debugging, Packaging and Building

I had used both Android Emulator(Installed as part of the setup) and Real Device to debug the application. The Footer bar of the VS Code shows the devices you are connected to and you can select one while debugging the code.

To Build the APK, use following command:

flutter build apk

To install the APK on your device, connect the device with USB and use following command

flutter install -d DXXXXX0123456787

Where DXXXXX0123456787 is your Device Id.

TIPS on Deploying the APK

• Your app may use internet connection like the Prediction app. Make sure to add the following line in android/app/src/main/AndroidManifest.xml file:

<uses-permission android:name="android.permission.INTERNET" /> 

See this thread for more details.

• You might want to customize the Launch Icon of your app, like Add the icon under folders named starts with mipmap-. These can be located under, android\app\src\main\res. Then modify the AndroidManifest.xml file to point to the image/icon as

android:icon="@mipmap/icon">

Please note, the same file can be edited to provide the suitable App name and description as well.

Publishing the app to the APP Store

If you have followed it so far, you have done 70% of it already. Please follow the links for doing the rest of it:

• Android
• IOS

That's All about it. It's very simple and super easy. Above all, pure fun!

Code

Feel free to clone and enhance the code from GitHub

https://github.com/atapas/horoscope-app

You can See the app in full action in the following video(30 seconds):

https://www.youtube.com/watch?v=ZLYFX18TQCA

What's Next

Next, I would like to interact with Hardware like, Camera, Bluetooth and try out the ML Vision with Firebase. Stay Tuned!

Credit

• Cover icons made by Freepik from www.flaticon.com is licensed by CC 3.0 BY

Hope you liked the start. Please let me know what's your experience with the mobile app development or with flutter. I will be glad to learn from your likes and dislikes of it.

Keep reading, Keep following, Keep sharing!

This story was originally Published here