Flutter Plugins: How to Use Third-Party Libraries in Your App

As a mobile app developer, you'll often find yourself in a situation where you need to use functionalities that are beyond the framework's scope. Fortunately, you can use third-party libraries to implement such features. And if you're using Flutter, using plugins is the way to go.

Plugins in Flutter allow you to use platform-specific code (Android or iOS) in your app. This means that you can access the native capabilities of the device, such as the camera or contacts. What's more, you can use the many plugins available in the Flutter community to implement complex functionalities with minimal effort.

In this article, we'll dive into the world of Flutter plugins and show you how to use them in your next app.

Understanding Flutter Plugins

In Flutter, plugins are packages that you can import into your app and use to implement specific functionalities. Plugins are usually built and maintained by the Flutter community, and you can find them on the official Flutter package repository - pub.dev.

Plugins perform a variety of tasks, including accessing device hardware, interacting with web APIs, and performing math operations. There are plugins for File Manipulation, Connectivity, Firebase or even Google Maps integration.

Flutter plugins can be of two types:

1. Dart-only plugins: These plugins are pure Dart code and can be easily used across different platforms. They are typically used for implementing functionalities that don't require accessing platform-specific code.

2. Platform-specific plugins: These plugins contain native code (Swift/Objective C for iOS and Java/Kotlin for Android) and require additional setup on the native platform side. Platform-specific plugins provide access to native device functionalities and are used for implementing functionalities that aren't possible with Flutter code alone.

While it's easy to create a Flutter plugin, you also have to maintain it. There are some differences between the Android and iOS plugin development, and you should consider these differences while building the plugin.

As an app developer, you can quickly integrate plugins into your app by adding them to your app's dependencies. Let's learn how to do this.

Adding a Plugin to Your Flutter Project

To add a plugin to your Flutter project, you'll need to perform the following steps:

1. Find the package: Go to pub.dev and search for the package that you want to use. Once you've found it, make a note of its package name (e.g. flutter_auth0) and the version that you want to use.

2. Add the package to your pubspec.yaml file: Open your Flutter project's pubspec.yaml file and add the package to your dependencies.

   dependencies:
     flutter_auth0: ^0.1.0
   

   Replace flutter_auth0 with the package name, and replace ^0.1.0 with the version that you want to use.

3. Install the package: Run the following command to install the package:

   flutter pub get
   

   This will download and install the package.

That's it! You've added the package to your project, and you're ready to start using it. Let's see how to use a plugin in your Flutter app.

Using a Plugin in Your Flutter App

To use a plugin in your Flutter app, you'll need to follow these steps:

1. Import the package: Import the package into your Dart file.

   import 'package:flutter_auth0/flutter_auth0.dart';
   

   Replace flutter_auth0 with the package name.

2. Create an instance of the plugin: Create an instance of the plugin and configure it with your credentials.

   final auth0 = Auth0(
     clientId: 'your_client_id',
     domain: 'your_domain.auth0.com',
   );
   

   Replace your_client_id and your_domain with your credentials.

3. Use the plugin: Use the plugin's methods to interact with the functionality it provides.

   Future<void> login() async {
     try {
       await auth0.webAuth.authorize({
         'response_type': 'token',
         'client_id': '${auth0.clientId}',
         'redirect_uri': 'myapp://login-callback',
         'audience': 'https://${auth0.domain}/userinfo',
       });
     } catch (e) {
       print('Error: $e');
     }
   }
   

In this example, we're using the webAuth method of the Auth0 plugin to authenticate the user. Notice that we're passing a configuration object to the authorize method.

You'll need to consult the documentation of the plugin that you're using to understand how to configure and use it.

Creating a Custom Plugin

While there are many plugins available in the Flutter community, you may find yourself in a situation where you need to implement a functionality that doesn't rely on any existing plugin. In such situations, you can create a custom plugin.

To create a custom plugin, you'll need to perform the following steps:

1. Create a new Flutter project: Create a new Flutter project using the following command:

   flutter create --org com.example my_plugin
   

2. Create a new plugin project: Create a new plugin project using the following command:

   flutter create --template=plugin --org com.example my_plugin/my_plugin
   

   Replace my_plugin with the name of your plugin.

3. Implement the plugin: Implement the functionality that your plugin provides. You'll need to create platform-specific code for both Android and iOS.

   class MyPlugin {
     static const MethodChannel _channel =
         const MethodChannel('my_plugin');
   
     static Future<String> get platformVersion async {
       final String version = await _channel.invokeMethod('getPlatformVersion');
       return version;
     }
   }
   

   In this example, we're using the MethodChannel class to interact with the native platform's code. Notice that we're invoking the getPlatformVersion method on the _channel instance.

   You'll need to set up the native code to handle the method invocation. For Android, you'll need to create a FlutterMethodCallHandler that listens to method calls from Dart.

   public class MyPlugin implements MethodCallHandler {
     private final MethodChannel channel;
   
     MyPlugin(MethodChannel channel) {
       this.channel = channel;
       channel.setMethodCallHandler(this);
     }
   
     @Override
     public void onMethodCall(@NonNull MethodCall call, @NonNull Result result) {
       if (call.method.equals("getPlatformVersion")) {
         result.success("Android " + android.os.Build.VERSION.RELEASE);
       } else {
         result.notImplemented();
       }
     }
   }
   

   similarly, for iOS, you'll need to create a Swift or Objective-C class that handles the method invocation.

   Now, that's a lot of code, but this plugin just returns the platform version. It's also worth mentioning that Flutter makes it easy to bind to the native platform API.

4. Publish the plugin: Finally, you'll need to publish your plugin on pub.dev so that others can use it.

   To publish a plugin, follow these steps:

   1. Create a pub.dev account: Create an account on pub.dev.

   2. Create a package: Create a package with the same name as your plugin. Make sure to follow the naming conventions.

   3. Upload the package: Upload the package to pub.dev using the following command:

      flutter packages pub publish --dry-run
      

      This will upload the package to pub.dev but will test it first. Make sure that you pass the --dry-run option while testing.

   4. Publish the package: Once you're satisfied with the package, upload it for real using the following command:

      flutter packages pub publish
      

That's it! You've created your first custom Flutter plugin.

Conclusion

Flutter plugins are a powerful tool that allows you to use third-party libraries in your app seamlessly. It's effortless to integrate a plugin into your app, and you can implement complex functionalities with minimal effort.

In this article, we've covered the basics of Flutter plugins, how to add a plugin to your project, and how to use it. We've also created a custom Flutter plugin.

Plugins are ubiquitous, and there is a plugin for almost any functionality you might need. You can create your plugin, and with the experience gained from building and maintaining your plugin, you'll finally be able to investigate bugs from root to tip in case you experience one with plugins you're using.

In conclusion, Flutter plugins are a game-changer in mobile app development, and we hope this article has shown you how to use them effectively while developing your next Flutter app.

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