You may not even notice but you are already doing it
One of the reasons why you decided to use Xamarin was that you want a complete shared-code solution for iOS, Android… and Windows Phone. That’s because Xamarin development helps you to achieve cross-platform goals. By using shareable PCLs or Shared Projects, you already have about 75-90% of shared code, which may be used in Windows Phone project as well. So you have more than half way done.
Alternatively you should consider to use Xamarin.Forms instead of traditional Xamarin approach. I always highly recommend to use Xamarin.Forms for utility or prototyping applications. The simplicity of that solution is just hilarious and as a profit you will support all three platforms at once (with Windows Phone from version 8.0+).
It’s incredibly easy to handle platform-specific code with Xamarin.Forms. Especially when it comes to UI layer, which will be described only once with shared set of controls that still render a native UI. So you will produce less non-shareable code to do same thing. As far as I’m concerned, the less is better.
It’s easier than you were thinking
According to previous paragraph some components, business logic, network access and other common services are re-used on each platform. What do you really need to do for fully native Windows Phone application is only a platform-specific code that will include UI definition, event handlers and sometimes some unique services to the platform.
To define Windows Phone interface you will use XAML, which is the same language that is fully supported in Xamarin.Forms. So UI definition and events shouldn’t be a problem even for those developers which know Windows Phone only from Xamarin University sessions.
It’s a great opportunity for you & your application
The main criticism of Windows Phone Store is still the lack of applications when compared to iOS and Android. This has an impact on lower sales of devices with this system, and as a result, on the popularity of the platform itself. For your application it’s a great opportunity, because it means that your app won’t run across so much competition. As a result, it will be easier to promote it, and success of the one platform (Windows Phone) is certainly not remain unanswered on other platforms.
Currently, looking at the data, Windows Phone shows up as a real contender in Europe, where the smartphone OS secured its spot with 10.1% market share across the UK, France, Spain, Germany and Italy. This is almost half of iOS market share! Supporting three major smartphone OS taking the lion share of the mobile OS space is your profit. In other words your application will run on a total of 2.6 billion devices.
Give me other reasons
To sum up – I am sure that there are others reasons why supporting Windows Phone with Xamarin is your profit. If you know other reasons, email me and I’ll cover them in the next article.