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Flutter Tutorial for Mobile Developers: A Complete Tutorial on Cross-Platform Development

Last updated on Jun 20,2023 853 Views


Flutter – the ultimate toolkit for creating visually stunning and highly performant mobile applications.” Flutter uses one code base for multiple mobile platforms want to know more about flutter then you have come to the right place. Hi everyone, I welcome you all to explore flutter in this session on the flutter tutorial with the following topics:

What is flutter?

Flutter, a mobile application development framework developed by Google, is open-source and enables developers to create high-performance, cross-platform mobile applications for iOS, Android, and the web using a single codebase. The framework uses the Dart programming language, also developed by Google, and provides a wide range of customizable widgets and tools for building beautiful and responsive user interfaces.

The hot reload feature of Flutter is a significant advantage, allowing developers to instantly see the changes they make to their code reflected in the app without restarting it. This speeds up the development process and makes it easier to iterate on designs and features.

Flutter’s architecture is based on widgets, the fundamental building blocks of the user interface, which can be combined and nested to create complex UI elements. Widgets can also be animated and customized to produce visually stunning effects. Additionally, Flutter includes APIs for working with networking, databases, and other system-level services.

Flutter’s performance is another advantage, as it uses its own rendering engine to deliver high frame rates and smooth animations, even on less powerful devices. The framework has a smaller footprint than some other frameworks, resulting in smaller and faster-to-download-and-install apps.

Flutter has gained popularity among developers and has been utilized in various industries, including finance, healthcare, education, and gaming. Companies such as Alibaba, Tencent, and BMW have also employed Flutter to build their apps.

Why use Flutter? 

Flutter is a popular open-source UI development framework created by Google, that allows developers to build high-performance, visually appealing mobile apps for Android, iOS, and web platforms using a single codebase.

Some reasons why developers choose to use Flutter:

  1. Faster development: Flutter provides a hot reload feature that allows developers to see changes instantly without restarting the app, making development faster and more efficient.
  2. Cross-platform development: Flutter’s single codebase allows developers to build apps for multiple platforms, including iOS, Android, and web, saving time and effort.
  3. Highly customizable UI: Flutter’s rich set of customizable widgets make it easy to create visually appealing, responsive user interfaces for apps.
  4. High-performance apps: Flutter’s reactive programming model and Dart language provide high-performance and smooth animations, resulting in a better user experience.
  5. Open-source and growing community: Flutter is an open-source framework with a large and growing community of developers and contributors, providing continuous support, new features, and bug fixes.


Flutter is a great option for developers who want to build beautiful, fast, and responsive mobile apps for multiple platforms using a single codebase.

Setting Up the Development Environment

flutter tutorial

Flutter vs other mobile development frameworks

The comparison table between Flutter and other popular mobile development frameworks:

FeatureFlutterReact NativeNativeScriptIonic
LanguageDartJavaScriptJavaScriptTypeScript
Platform supportiOS, Android, web, desktop, and embeddediOS, Android, webiOS, AndroidiOS, Android, web, desktop
UI DevelopmentWidget tree structure, supports custom rendering and animationsComponent-based, with access to native UI componentsComponent-based, with access to native UI componentsComponent-based, with access to native UI components
PerformanceFast, efficient, and highly customizableSlower than native performanceSlower than native performanceSlower than native performance
Development speedFast development cycles and hot reload for faster iterationsFast development cycles and hot reload for faster iterationsFast development cycles and hot reload for faster iterationsFast development cycles and hot reload for faster iterations
Community and supportGrowing community and extensive documentationLarge community with active contributorsGrowing community with good documentationLarge community with active contributors
Learning curveEasy to learn, especially for developers familiar with object-oriented programmingSteep learning curve for developers without React experienceModerate learning curve for developers with JavaScript experienceEasy to learn, especially for developers familiar with Angular
Integration with native codeSupports platform-specific features through pluginsSupports platform-specific features through pluginsSupports platform-specific features through pluginsSupports platform-specific features through plugins


Please note that this table provides a general comparison between these frameworks and may not cover all the aspects of each framework.

Installing Flutter SDK and required tools

Installing Flutter and the required tools can be done by following these steps:

  • Download the Flutter SDK from the official Flutter website (https://flutter.dev/docs/get-started/install).
  • Extract the downloaded file to your desired location.
  • Add the Flutter SDK to your system path. This can be done by adding the following line to your shell configuration file (e.g. .bash_profile, .zshrc, etc.):

export PATH="$PATH:[PATH_TO_FLUTTER_DIRECTORY]/flutter/bin"
Make sure to replace [PATH_TO_FLUTTER_DIRECTORY] with the actual path to the directory where you extracted the Flutter SDK.

  • Install the required dependencies:
    • For macOS: Install Xcode and its Command Line Tools.
    • For Windows: Install the Visual Studio Code with the Flutter and Dart extensions, and also the Android Studio.
    • For Linux: Install the required libraries and tools.
  • Detailed instructions can be found on the official Flutter website.
  • Verify that Flutter is installed correctly by running the following command in your terminal:

flutter doctor
This command will check your environment and display a report of the status of your Flutter installation.

That’s it! You’re now ready to start building Flutter apps.

Setting up an IDE 

To set up an IDE for Flutter development, follow these steps:

    1. Install Android Studio or Visual Studio Code.
    2. Install the Flutter and Dart plugins for your IDE. This can be done by navigating to the IDE’s extensions marketplace and searching for “Flutter” and “Dart”.
    3. Open your Flutter project in the IDE.
      • If you’re using Android Studio, select “Open an existing Android Studio project” and navigate to your project directory.
      • If you’re using Visual Studio Code, open your project folder using the “Open Folder” command.
    4. Verify that your IDE is set up correctly by running your app on an emulator or physical device.
      • For Android Studio:
        • Click on the “Run” button in the toolbar, or press Shift + F10.
        • Select the target device from the dropdown menu, or create a new virtual device if needed.
        • Click “OK” to start the app.
      • For Visual Studio Code:
        • Open the command palette using Ctrl + Shift + P (or Cmd + Shift + P on macOS).
        • Type “Flutter: Run Flutter App” and select the command from the list.
        • Select the target device from the dropdown menu, or create a new virtual device if needed.
        • Click “OK” to start the app.

That’s it! You’re now ready to start developing Flutter apps in your IDE.

Creating a new Flutter project

the steps to create a new Flutter project using Android Studio:

  1.  After installing Android Studio and Flutter, open Android Studio.
  2. Click “Start a new Flutter project”: On the welcome screen, click “Start a new Flutter project”. If you have a project already opened, you can also start a new Flutter project by going to “File” > “New” > “Flutter Project”.
  3. Choose a project type: Select the type of project you want to create, such as “Flutter Application”, “Flutter Plugin”, or “Flutter Package”. Then click “Next”.
  4. Enter project details: Enter the project details such as project name, package name, project location, etc. Then click “Next”.
  5. Choose a Flutter SDK: Choose the Flutter SDK path that you installed earlier. If you installed Flutter using the default installation location, Android Studio will automatically detect it. Then click “Next”.
  6. Choose project settings: Choose the settings for your project such as platform, language, etc. Then click “Finish”.
  7. Wait for the project to be created: Android Studio will create the project and download any necessary dependencies.

That’s it! You now have a new Flutter project created in Android Studio. You can start building your app by modifying the code in the lib/main.dart file.

Basic Flutter Concepts

Flutter Tutorial intro

Widgets

In mobile application development, a widget is a component that displays information or provides a specific functionality on the user interface of a mobile device, such as a smartphone or a tablet. A mobile widget can be a standalone application or a part of a larger application, and it can be placed on the home screen, lock screen, or in the notification area of a mobile device.

Examples of mobile widgets include:

  • Weather widget
  • Music player widget
  • Calendar widget
  • Clock widget
  • Social media widget


Mobile widgets can be interactive, allowing users to perform certain actions directly from the widget without opening the full app. They can also be customized by the user, such as changing the size, position, or appearance of the widget.

Stateful vs stateless widgets

Widgets can be classified as either stateful or stateless, depending on whether or not they can maintain their internal state.

Stateful WidgetStateless Widget
Has mutable stateDoes not have mutable state
Can change appearance/behavior based on stateAlways appears the same regardless of state
Rebuilds on state changeDoes not rebuild on state change
Implemented using StatefulWidget classImplemented using StatelessWidget class
Used for dynamic contentUsed for static content

A stateful widget is a widget that has mutable state and can change its appearance or behavior based on the state. When the state of a stateful widget changes, the widget rebuilds itself to reflect the new state. For example, a text input field widget would be a stateful widget because it needs to maintain and update the text value entered by the user. A stateful widget is implemented using the StatefulWidget class in Flutter.

On the other hand, a stateless widget is a widget that does not have mutable state and always appears the same way, regardless of the state of the app. A stateless widget is implemented using the StatelessWidget class in Flutter. Examples of stateless widgets include display widgets like text, images, icons, and buttons that don’t change their appearance or behavior based on user input.

Stateful widgets are useful for implementing features that require dynamic user input and real-time updates, such as forms, animations, and scrolling lists. Stateful widgets can be more complex to implement than stateless widgets since they need to manage their own state and update the user interface accordingly.

Stateless widgets, on the other hand, are useful for displaying static content that doesn’t change based on user input. They are simpler to implement than stateful widgets and can be more efficient since they don’t need to rebuild themselves when the app state changes.

Layouts

Layouts in mobile applications refer to the way that user interface components are arranged on the screen of a mobile device. The layout is critical to the overall look and feel of the application and can greatly affect the user experience. In mobile application development, different types of layouts are used depending on the design and functionality of the app.

Here are some common layouts used in mobile app development:

  1. Linear layout: A linear layout arranges user interface components in a single row or column. This layout is often used to create simple, linear lists or grids of items.
  2. Relative layout: A relative layout positions user interface components relative to one another. This layout is often used for more complex layouts where the position of components needs to be flexible.
  3. Constraint layout: A constraint layout is similar to a relative layout, but it uses constraints to specify the position and size of user interface components. This layout is often used for complex and dynamic layouts.
  4. Table layout: A table layout arranges user interface components in a grid of rows and columns. This layout is often used to display tabular data or to create forms.
  5. Frame layout: A frame layout places user interface components on top of each other in a stack. This layout is often used for animations or for creating layered user interface components.
  6. Grid layout: A grid layout arranges user interface components in a grid of rows and columns, similar to a table layout. This layout is often used for more complex grids with varying column and row sizes.


layouts in flutter tutorial

Choosing the right layout for a mobile application depends on the design and functionality of the app. Developers need to consider factors like the size and orientation of the device, the type of content being displayed, and the user experience they want to create. A well-designed layout can greatly enhance the user experience and make the app more user-friendly and intuitive to use.

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Navigation

Mobile application navigation refers to the way users move through different screens, menus, and sections within an app. It is an essential part of mobile app design that helps users to complete tasks and find the content they need quickly and efficiently.

Effective mobile app navigation involves creating an interface that is easy to use and intuitive. Users should be able to access the most important features and content within the app with just a few taps or gestures. The navigation menu should be visible and accessible at all times, making it easy for users to move between different screens or sections of the app.

Mobile app navigation can take many forms, including:

  1. Tab-based navigation: This involves placing tabs at the bottom of the screen that allow users to switch between different sections of the app.
  2. Hamburger menu: This is a common navigation pattern that involves placing a menu icon (three horizontal lines) in the top left or right corner of the screen. When tapped, the menu slides open, revealing additional options or sections.
  3. Floating action button (FAB): This is a circular button that appears at the bottom of the screen and is used to perform a primary action within the app.
  4. Gestures: Mobile apps can use various gestures, such as swiping, tapping, or pinching, to navigate between screens or access additional menus or features.

When designing mobile app navigation, it’s important to consider the needs and preferences of your target audience. For example, younger users may be more comfortable with gestures and swipes, while older users may prefer traditional navigation patterns such as tabs and menus.

Overall, effective mobile app navigation is critical to providing a smooth and seamless user experience. By designing an intuitive and easy-to-use interface, you can help users complete tasks and find the content they need quickly and efficiently, leading to a better overall user experience.

Building a Basic Flutter App

Creating a home screen

Creating a home screen in Flutter involves creating a widget tree that represents the UI of your home screen. Here are the general steps to create a home screen in Flutter:

  1. Create a new Flutter project or open an existing one in your preferred IDE.
  2. Open the main.dart file and create a new StatefulWidget.

 

class MyHomePage extends StatefulWidget {

 @override

 _MyHomePageState createState() => _MyHomePageState();

}
  1. Create a state class that extends the State of MyHomePage.

 

class _MyHomePageState extends State<MyHomePage> {

@override

Widget build(BuildContext context) {

return Scaffold(

appBar: AppBar(

title: Text('My Home Page'),

),

body: Container(

child: Center(

),

),

),

);

}

}
  • Inside the build method of _MyHomePageState, create a Scaffold widget with an AppBar and a body. You can customize the AppBar with a title or other properties as needed.
  • In the body of the Scaffold, add a widget that represents the content of your home screen. This can be a simple Text widget or a more complex widget tree that includes images, buttons, and other UI elements.
  • Run the app and verify that your home screen is displayed correctly.

Here’s an example of a home screen that displays an image and a button:

 

class _MyHomePageState extends State<MyHomePage> {

@override

Widget build(BuildContext context) {

return Scaffold(

appBar: AppBar(

title: Text('My Home Page'),

),

body: Container(

child: Column(

mainAxisAlignment: MainAxisAlignment.center,

children: [

Image.asset('assets/images/logo.png'),

SizedBox(height: 20),

ElevatedButton(

onPressed: () {},

child: Text('Get Started'),

),

],

),

),
);
}
}

In this example, the home screen contains a Column widget that includes an Image widget and an ElevatedButton widget. The mainAxisAlignment property of the Column is set to MainAxisAlignment.center to center the content vertically, and a SizedBox widget is used to add some spacing between the image and the button. The onPressed callback of the button is empty for now, but you can add your own logic to handle user input.

Adding widgets and layouts

To add widgets and layouts to the home screen in a Flutter app, follow these steps:

  1. In the _HomeScreenState class, replace the Center widget in the body property of the Scaffold with a Column widget:

body: Column(
mainAxisAlignment: MainAxisAlignment.center,
children: [
Text('Welcome to my app!'),
RaisedButton(
child: Text('Press me!'),
onPressed: () {
// TODO: add button press logic
},
),
],
),

The Column widget arranges its children vertically. In this case, we’re using the mainAxisAlignment property to center the children vertically. The children of the Column widget are two widgets: a Text widget with the welcome message, and a RaisedButton widget with a label and an onPressed callback. The onPressed callback will be called when the button is pressed, and we’ll add some logic to it in the next step.

  1. Inside the onPressed callback of the RaisedButton widget, add some logic to display a message in a Snackbar widget:

onPressed: () {
Scaffold.of(context).showSnackBar(SnackBar(
content: Text('You pressed the button!'),
));
},

This code uses the Scaffold.of(context) method to get a reference to the Scaffold widget, and then calls the showSnackBar method to display a Snackbar widget with a message. The context argument is passed to the method to provide the context of the current widget.

  1. Finally, add an Image widget to the Column widget to display an image:

body: Column(
mainAxisAlignment: MainAxisAlignment.center,
children: [
Text('Welcome to my app!'),
RaisedButton(
child: Text('Press me!'),
onPressed: () {
Scaffold.of(context).showSnackBar(SnackBar(
content: Text('You pressed the button!'),
));
},
),
Image.asset('assets/images/my_image.png'),
],
),


This code uses the Image.asset constructor to create an Image widget that displays an image from the assets/images directory of the app. Replace “my_image.png” with the actual filename of your image.

When you run the app now, you should see the welcome message, button, and image displayed on the screen. When you press the button, a Snackbar widget should appear with a message.

Implementing basic navigation

To implement basic navigation in a Flutter app, follow these steps:

  1. Create a new screen widget called “SecondScreen” by defining a new StatefulWidget:

class SecondScreen extends StatefulWidget {
@override
_SecondScreenState createState() => _SecondScreenState();
}

  1. In the _SecondScreenState class, override the build method to return a Scaffold widget with some content:

class _SecondScreenState extends State<SecondScreen> {
@override
Widget build(BuildContext context) {
return Scaffold(
appBar: AppBar(
title: Text('Second Screen'),
),
body: Center(
child: Text('This is the second screen!'),
),
);
}
}

This code creates a new screen with an AppBar and a Text widget as the body.

  1. In the _HomeScreenState class, replace the RaisedButton widget with a FlatButton widget and add an onPressed callback to navigate to the second screen:

FlatButton(
child: Text('Go to second screen'),
onPressed: () {
Navigator.push(
context,
MaterialPageRoute(builder: (context) => SecondScreen()),
);
},
),

This code uses the Navigator.push method to navigate to the second screen when the button is pressed. The MaterialPageRoute class creates a new route for the second screen and provides a builder method to create the widget that will be displayed on the screen.

  1. In the main.dart file, add a new route for the second screen:

void main() {
runApp(
MaterialApp(
initialRoute: '/',
routes: {
'/': (context) => HomeScreen(),
'/second': (context) => SecondScreen(),
},
),
);
}

This code adds a new route for the second screen with a path of ‘/second’. Now, when you call Navigator.push with the SecondScreen widget, Flutter will automatically navigate to the ‘/second’ route and display the SecondScreen widget.

  1. In the _HomeScreenState class, update the onPressed callback to navigate to the second screen using the named route:

FlatButton(
child: Text('Go to second screen'),
onPressed: () {
Navigator.pushNamed(context, '/second');
},
),


This code uses the Navigator.pushNamed method to navigate to the second screen using the named route ‘/second’. This is a more convenient way to navigate between screens because you can define all of your routes in one place and refer to them by name.

When you run the app now, you should see the home screen with a button to navigate to the second screen. When you press the button, the app should navigate to the second screen and display its content.

Adding Functionality to the App
Handling user input

To handle user input in a Flutter app, you can follow these steps:

  1. Create a new TextEditingController variable to keep track of the user input.
  2. Replace a Text widget with a TextField widget to allow the user to input text. Bind the TextField widget to the TextEditingController variable.
  3. Update the onPressed callback of the button or widget to retrieve the text entered by the user using the text property of the TextEditingController variable.
  4. Dispose of the TextEditingController variable in the dispose method of the widget to avoid memory leaks.

Working with data and APIs

Flutter is a mobile app development framework that allows developers to build high-performance, native mobile applications for both iOS and Android platforms using a single codebase. One of the key components of building a mobile app is working with data and APIs.

In simple terms, APIs are a way for different applications to communicate with each other. In the context of a mobile app, APIs allow the app to send and receive data from a remote server. This data could be anything from user information to a list of products to display in the app.

Here are the basic steps for working with data and APIs in a Flutter project:

  1. Make a request to the API: To retrieve data from an API, you need to make an HTTP request. This request specifies the endpoint (URL) of the API and any parameters needed to retrieve the desired data.
  2. Handle the response: After making the request, the API will respond with data. This response may be in JSON format, which is a common format for transmitting data over the internet. In a Flutter project, you can use packages like http or dio to make the HTTP request and parse the JSON response.
  3. Display the data: Once you’ve retrieved the data from the API, you can display it in your app’s user interface. Depending on the type of data you’re working with, you might display it in a list, a table, or a map, for example.
  4. Update the data: If your app allows users to interact with the data, you may need to update the data on the server using another API request. This could be anything from adding a new item to a shopping cart to updating a user’s profile information.

In summary, working with data and APIs in a Flutter project involves making HTTP requests to retrieve data, handling the JSON response, displaying the data in your app’s UI, and possibly updating the data on the server. There are many libraries and packages available in Flutter that make working with data and APIs easier, but understanding the basics is key to building a successful mobile app.

Incorporating Third-Party Packages

Flutter has a vast ecosystem of third-party packages that can be used to add new functionalities and features to your app. These packages can be easily integrated into your project by adding them to the pubspec.yaml file, which is a configuration file for your app’s dependencies. Once the package is added, you can import it into your code and start using it.

When choosing a third-party package, it’s important to ensure that it is actively maintained, has good documentation, and is compatible with the current version of Flutter that you’re using. Additionally, you should also consider the package’s size and whether it will add unnecessary bloat to your app.

Testing and Debugging:

Testing and debugging are critical steps in the development process that help ensure that your app works as expected and is free of bugs and errors. In Flutter, you can test your app using either an emulator or a physical device.

Testing on an emulator or physical device:

Flutter provides emulators for both iOS and Android platforms, which can be used to test your app on different screen sizes, resolutions, and versions of the operating system. When testing on an emulator, it’s important to ensure that the emulator is configured to match the device that you’re targeting, including the screen size, orientation, and pixel density.

In addition to emulators, you can also test your app on a physical device. To do this, you’ll need to connect your device to your computer using a USB cable and enable developer mode on the device. Once the device is connected, you can run your app directly on the device and test its functionality.

Debugging common errors:

Debugging is the process of identifying and fixing errors in your code. In Flutter, you can use the built-in debugging tools to help you identify and fix common errors, such as null pointer exceptions and syntax errors.

Flutter provides a rich set of debugging tools, including the Flutter DevTools, which is a browser-based tool that provides insights into the performance of your app, as well as the Flutter Inspector, which allows you to inspect the widget tree and debug layout issues.

Publishing the App:

Once you’ve tested and debugged your app, it’s time to prepare it for release and publish it to the Google Play Store or Apple App Store. Here’s what you need to do:

Preparing the app for release:

Before you can publish your app, you’ll need to ensure that it meets all the requirements of the app store, including the app’s size, user interface, functionality, and content. You’ll also need to generate a signed APK (Android) or IPA (iOS) file, which is a secure version of your app that can be uploaded to the app store.

Uploading the app to the Google Play Store or Apple App Store:

To publish your app, you’ll need to create a developer account on the Google Play Store or Apple App Store and follow the guidelines for submitting your app. This includes providing metadata such as the app’s name, description, screenshots, and app icon, as well as setting the app’s pricing and distribution options.

Once your app has been submitted, it will undergo a review process to ensure that it meets all the guidelines and policies of the app store. This process can take several days or even weeks, depending on the complexity of your app and the number of submissions that the app store is currently receiving.

This brings us to the end of this blog on what is Flutter. Hope I was able to clearly explain  Flutter Tutorial and why you should use it. 

If you want to get trained in Flutter and wish to develop interesting UI’s on your own, then check out the best Flutter Course offered by Edureka, Our Flutter Course Syllabus, curated by industry experts that will help you to master its all concepts.

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