Using Native Libraries with Xamarin Binding

Xamarin Binding is a powerful technology that allows mobile app developers to make native libraries prepared for Android or iOS usable in a .NET environment. In Xamarin projects, the importance of the Xamarin Binding process comes to the fore, especially when custom hardware drivers or third-party SDKs need to be used. In this article, we will explain in detail what Xamarin Binding is, its usage scenarios, and how to integrate a sample Java library into a Xamarin.Android project.

What is Xamarin Binding and Why is it Used?

Xamarin Binding is a bridge solution that allows external libraries prepared with Objective-C (iOS) or Java (Android) to be accessed as managed code in the .NET/C# environment. In this way, your application developed with Xamarin can functionally include all native features and libraries supported by the platform. Xamarin Binding reduces the need to rewrite native code and maintenance costs in projects that require special SDKs for cross-platform development.

Creating a Binding Library for Xamarin.Android

Creating a Binding Library Project

For example, let's enable using a Java library in .jar or .aar format written for Android with Xamarin. Start a new Xamarin.Android Binding Library project in Visual Studio. After creating the project, add the native library to the Jars folder in the binding library and choose EmbeddedJar or LibraryProjectZip as the Build Action.

// After adding the Java library to the project, you can call the native library with the automatically generated C# interfaces
public class SampleClass : Java.Lang.Object
{
    public void CallNativeMethod()
    {
        // You can use the functions coming with the binding here
    }
}

Metadata Development and Customization

Sometimes the binding tool cannot generate all members as desired automatically. In this case, you can edit the Metadata.xml file in the project to manage naming, access, and removal operations on the C# side API. For example, to export only a specific method, you can define it as follows:

<metadata>
  <remove-node path="/api/package[@name='com.ornek.kutuphane']/class[@name='UnwantedClass']" />
</metadata>

Using the Binding Library in the Xamarin Project

After creating the binding library, you can add the generated .dll file to the main Xamarin.Android project as a reference and call native functions directly. In this way, thanks to Xamarin Binding, it is possible to use all the features offered by the native library in the .NET ecosystem.

Conclusion: Contributions of Xamarin Binding

With Xamarin Binding, you can combine existing native Android and iOS libraries with the advantages of the C# language. Especially for the integration of local or third-party services and platform-specific needs, Xamarin Binding makes a significant difference. With a properly configured Binding Library, code duplication is prevented and it becomes easier to benefit from up-to-date native libraries.