**Course Title:** .NET MAUI App Development **Section Title:** Cross-Platform Development & Platform-Specific Code **Topic:** Understanding platform-specific code and APIs As a .NET MAUI developer, you've learned how to build cross-platform applications that share a significant amount of code across different platforms, including Android, iOS, and Windows. However, there are situations where you need to access platform-specific features or APIs to create a more native experience for your users. In this topic, we'll explore how to write platform-specific code and use APIs to access native features. ### Why Platform-Specific Code? While .NET MAUI provides a shared codebase for cross-platform development, there are scenarios where you need to access platform-specific features that are not available through the shared codebase. Some examples include: * **Native Hardware**: Accessing hardware features such as GPS, camera, or fingerprint reader that are unique to each platform. * **Platform-Specific APIs**: Using APIs that are specific to each platform, such as Android's Google Maps API or iOS's Core Location API. * **Native UI**: Creating platform-specific UI elements that are not available through XAML or shared codebase, such as Android's Notification Shade or iOS's Control Center. ### Mechanisms for Platform-Specific Code .NET MAUI provides several mechanisms to write platform-specific code: * **Platform-Specific Projects**: Create separate projects for each platform to contain platform-specific code. * **Conditional Compilation**: Use conditional compilation directives to include platform-specific code in your shared project. * **Dependency Service**: Use the Dependency Service to resolve platform-specific implementations of interfaces. ### Platform-Specific Projects Platform-specific projects are separate projects that contain code specific to each platform. These projects are typically used for complex platform-specific implementations, such as native UI components or hardware access. Here's an example of how you can create a platform-specific project for Android and iOS: **Project Structure:** ```csharp MyApp (solution) |--- MyApp (shared project) |--- MyApp.Android (platform-specific project) |--- MyApp.iOS (platform-specific project) ``` In this structure, `MyApp.Android` and `MyApp.iOS` contain platform-specific code for Android and iOS, respectively. ### Conditional Compilation Conditional compilation directives allow you to include platform-specific code in your shared project. You can use directives such as `#if __ANDROID__` or `#if __IOS__` to include code that is specific to each platform. Here's an example of using conditional compilation directives to include platform-specific code: ```csharp #if __ANDROID__ Console.WriteLine("Android platform"); #elseif __IOS__ Console.WriteLine("iOS platform"); #endif ``` ### Dependency Service The Dependency Service is a mechanism to resolve platform-specific implementations of interfaces. You can use it to decouple your platform-specific code from your shared codebase. Here's an example of using the Dependency Service to resolve a platform-specific implementation of an interface: ```csharp // Shared interface public interface IPlatformService { string GetPlatformName(); } // Android implementation [Droid] public class AndroidPlatformService : IPlatformService { public string GetPlatformName() { return "Android"; } } // iOS implementation [iOS] public class iOSPlatformService : IPlatformService { public string GetPlatformName() { return "iOS"; } } // Usage in shared code IPlatformService platformService = DependencyService.Get<IPlatformService>(); string platformName = platformService.GetPlatformName(); Console.WriteLine(platformName); ``` ### Managing Platform-Specific Code To manage platform-specific code effectively, follow these best practices: * **Keep it minimal**: Only use platform-specific code when necessary. * **Abstract platform-specific code**: Use interfaces and Dependency Service to decouple platform-specific code from your shared codebase. * **Use conditional compilation**: Use conditional compilation directives to include platform-specific code in your shared project. ### Conclusion In this topic, you've learned how to write platform-specific code and use APIs to access native features. You've also learned about the mechanisms available in .NET MAUI for writing platform-specific code, including platform-specific projects, conditional compilation, and Dependency Service. By following best practices and using these mechanisms effectively, you can create a more native experience for your users while maintaining a shared codebase.