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Software Development Executive - II
Last updated on Dec 27, 2024
Last updated on Aug 25, 2023
Flutter is a UI toolkit that allows you to create natively compiled applications for mobile, web, and desktop from a single codebase. One powerful aspect of Flutter is the ability to create plugins that enable developers to write native code that can then be called from their Dart code. In this guide, we'll be focusing on how to develop a Flutter plugin.
Flutter plugins are Dart packages that provide additional functionality not covered by the core libraries. They grant access to native platform APIs and services that aren't available in Dart or Flutter by default. Flutter plugin development is crucial because it allows developers to interact with native platform-specific features.
In setting out to create your own plugin, there's one key concept you should understand: the relationship between Dart code and platform-specific code. Flutter plugins bridge the gap between the Dart virtual machine and the platform APIs by using platform channels.
Flutter plugins extend the capabilities of Flutter apps by allowing them to tap into native functionality. This means that a Flutter app developed with plugins can handle complex tasks like payment processing or file system access, making the app more feature-rich and competitive.
A platform channel is a medium through which your Flutter app (Dart code) communicates with the native code. The channel connects the Dart UI to the platform's native APIs, giving your Dart file access to the platform-specific functionality. Platform channels are fundamental to the Flutter plugin architecture.
Before you can start developing your own Flutter plugin, it's necessary to get your development environment all set up.
Creating plugins requires Flutter SDK, an integrated development environment (IDE) like Android Studio, and a familiarity with the language for the platforms you plan to support (such as Java or Kotlin for Android, and Swift or Objective-C for iOS).
Setting up the Flutter plugin in Android Studio is a straightforward process.
Here's how you can do it:
As you venture deeper into Flutter plugin development, you'll encounter a term known as federated plugins.
Federated plugins are a method of separating platform support into independent packages. A federated plugin, for example, can use one package for iOS, another for Android, another for web, and even another for an IoT device such as a car. Federated plugins ensure a more effective and efficient approach to platform-specific code maintenance.
One substantial advantage of federated plugins is allowing different developers to extend an existing plugin to work on platforms they are most familiar with. This means that a domain expert can focus on an implementation for a specific platform, making the plugin more robust, performant, and secure.
Understanding the structure of federated plugins is important while developing your own federated plugin.
You can have two types of federated plugins – endorsed and non-endorsed ones. An endorsed plugin means the original author has included your implementation as an endorsed platform, while a non-endorsed one means your implementation hasn't been added by the original plugin author.
With the ever-evolving innovation in technology, VR (Virtual Reality) is making waves across various industries. Let's dive into developing a unique Flutter VR Plugin.
VR plugins have a unique role in enhancing applications with 3D front-end experiences and can make your application stand out. They can support complex, real-time interactions with 3D data, amplifying user engagements in your Flutter app to the next level.
Firstly, you need to create a VR activity. This VR activity is where all the major functionality related to VR is going to happen. Here's an example on how to create a VR activity:
1 class VRActivity : AppCompatActivity() { 2 override fun onCreate(savedInstanceState: Bundle?) { 3 super.onCreate(savedInstanceState) 4 // Your code ... 5 } 6 // Other functions ... 7 } 8
After creating and setting up your VR activity, you need to create the user interface (UI) components that handle the VR functionality of your Flutter app. These can include view controllers, renderers, motion handlers, and other essential components.
Plugin classification is vitally important. When you develop a Flutter plugin, you need to specify which platforms the plugin will support.
As part of the Flutter plugin development process, you'll specify the platforms your plugin supports by adding keys to the platforms map in the pubspec.yaml file. Here's an example of how it would look for a plugin that supports Android and iOS:
1 flutter: 2 plugin: 3 platforms: 4 android: 5 package: com.example.hello 6 pluginClass: HelloPlugin 7 ios: 8 pluginClass: HelloPlugin 9
Further extending the plugin's compatibility, we can add support for macOS and Web. Here's an example of how it should look in the pubspec.yaml file:
1 flutter: 2 plugin: 3 platforms: 4 android: 5 package: com.example.hello 6 pluginClass: HelloPlugin 7 ios: 8 pluginClass: HelloPlugin 9 macos: 10 pluginClass: HelloPlugin 11 web: 12 pluginClass: HelloPlugin 13 fileName: hello_web.dart 14
In the snippet above, you can see the plugin supports the Android, iOS, macOS, and web platforms (android, ios, macos, web).
Now we will dive deeper into the structure and implementation of federated platform packages. Such packages reside at the core of the federated plugins, underpinning their capabilities.
A federated platform package follows a similar structure to a basic plugin package. However, they contain an additional implements entry to indicate which app-facing package it implements. Here's an example:
1 flutter: 2 plugin: 3 implements: hello 4 platforms: 5 windows: 6 pluginClass: HelloPlugin 7
A platform package can be endorsed by adding a dependence on it and including it as a default_package in the platforms: map.
1 flutter: 2 plugin: 3 platforms: 4 android: 5 package: com.example.hello 6 pluginClass: HelloPlugin 7 ios: 8 pluginClass: HelloPlugin 9 windows: 10 default_package: hello_windows 11 12 dependencies: 13 hello_windows: ^1.0.0 14
In this example, "hello_windows" is an endorsed implementation of the "hello" plugin, and it is also added as a dependency in the pubspec.yaml file.
As shown, an app-facing package can have some platforms implemented within the package, and others in endorsed federated implementations. This allows more flexibility and opportunities for multiple developers to contribute their platform-specific expertise.
In the world of Flutter plugin development, it's common to encounter scenarios where a plugin necessitates the same or similar functionality on iOS and macOS platforms.
Flutter provides one unique functionality to satisfy this need: sharedDarwinSource. Many frameworks support both iOS and macOS with similar or almost equivalent APIs, allowing some plugins to be developed for both platforms using the same codebase.
We can configure iOS and macOS to use a shared folder, named dartwin, for all code and resources. Here's an example of how it should look in the pubspec.yaml file:
1 flutter: 2 plugin: 3 platforms: 4 ios: 5 pluginClass: HelloPlugin 6 sharedDarwinSource: true 7 macos: 8 pluginClass: HelloPlugin 9 sharedDarwinSource: true 10 11 environment: 12 sdk: ^3.0.0 13 # Flutter versions prior to 3.7 did not support the 14 # sharedDarwinSource option. 15 flutter: ">=3.7.0" 16
In this configuration, you will observe that both iOS and macOS utilize the same dartwin directory for all code and resources. This simplifies code maintenance by allowing a single codebase to serve both platform implementations.
Now that we've covered all the fundamentals, it's time to jump into the practical aspect and learn how to develop a Flutter plugin.
This is the preliminary and a significant step in the Flutter plugin development process. In this step, you'll be creating a plugin package using flutter create:
1 flutter create --org com.example --template=plugin --platforms=android,ios,linux,macos,windows -a kotlin hello 2
Here, the plugin package named 'hello' is created, which would support Android, iOS, Linux, macOS, and Windows platforms. The Kotlin language is specified for the Android platform.
Upon the successful creation of the plugin, the next step would be its implementation.
1 class HelloPlugin { 2 // Define API functions here 3 } 4
At this point, you are all set with the initial setup and have a broad understanding of how to develop a Flutter plugin.
Building upon the foundation we've created, let's now explore the role Dart plays, particularly when mixed with other platform-specific languages.
In many cases, non-web platform implementations only use the platform-specific implementation language, as shown in our earlier sections. However, platform implementations can also use platform-specific Dart as well.
In some cases, some platforms can be implemented entirely in Dart (for example, using FFI). Let's modify our previous 'hello_windows' example for a Dart-only implementation:
1 flutter: 2 plugin: 3 implements: hello 4 platforms: 5 windows: 6 dartPluginClass: HelloPluginWindows 7
In the above configuration, your Dart implementation replaces the previous C++ Windows code.
1 class HelloPluginWindows extends HelloPluginPlatform { 2 /// Registers this class as the default instance of [HelloPluginPlatform]. 3 static void registerWith() { 4 HelloPluginPlatform.instance = HelloPluginWindows(); 5 } 6 } 7
In some scenarios, platform implementations can use both Dart and a platform-specific language, forming a hybrid implementation:
1 flutter: 2 plugin: 3 implements: hello 4 platforms: 5 windows: 6 dartPluginClass: HelloPluginWindows 7 pluginClass: HelloPlugin 8
In the above configuration, the Dart plugin class 'HelloPluginWindows' works in tandem with the C++ class 'HelloPlugin'.
Last but certainly not least, we'll address an essential part of any development process - testing.
Testing your Flutter plugin is a crucial step in the development process. This ensures that your functionalities work as expected and don't regress as you make changes to your code, providing you with confidence that your plugin does what it's intended to do.
1 import 'package:flutter_test/flutter_test.dart'; 2 3 // Import your package 4 import 'package:hello/hello.dart'; 5 6 void main() { 7 TestWidgetsFlutterBinding.ensureInitialized(); 8 9 group('HelloPlugin', () { 10 const MethodChannel channel = MethodChannel('hello'); 11 12 setUp(() { 13 channel.setMockMethodCallHandler((MethodCall methodCall) async { 14 // Put your mock test logic here. 15 }); 16 }); 17 18 tearDown(() { 19 channel.setMockMethodCallHandler(null); 20 }); 21 22 // Write your tests here. 23 }); 24 } 25
This comprehensive guide walked you through every facet of Flutter plugin development. We dissected the process of creating a plugin package, understanding federated plugins, talked about incorporating VR functionality, and touched upon specifying platform support in your plugin. We dived into Dart platform implementations and seamlessly connected Dart code with platform-specific code. Lastly, we highlighted the enormous importance of regularly testing your plugin package. With these insights, we believe you're now well-prepared to handle Flutter and Dart complexities, presenting a great opportunity to upgrade your apps to deliver richer, more versatile user experiences. Happy Fluttering!
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