Merge pull request #817 from Azure/XamarinSupport

Build in C# using Xamarin for iOS and Android

csharp/device/doc/devbox_setup.md

@@ -31,9 +31,19 @@ If you are creating a client application from scratch, use the Visual Studio pac
 
 This repository contains various .NET sample applications that illustrate how to use the Microsoft Azure IoT device SDK for .NET. For more information, see the [readme][readme].
 
+## Building for iOS and Android using C#  
+For building for iOS and Android using C#, you need to install [Xamarin][lnk-visualstudio-xamarin] for VS 2015
+
+For building iOS sample, open **csharp\device\samples\DeviceClientSampleiOS** project file in VS 2015. You will be prompted to install Xamarin to build native iOS apps in C# if tool is not installed. Install the tool. You can test the sample on iPhone simulator running on your Mac.
+
+For building Andriod sample open **csharp\device\samples\DeviceClientSampleAndroid** VS project file in VS 2015. You will be prompted to install Xamarin to build native Android apps in C# if tool is not installed. Install the tool. You can test the sample on Android emulator running on you host PC.
+
+To check for any latest Xamarin update for Visual Studio check Tools->Options->Xamarin->Other.
 
 [visual-studio]: https://www.visualstudio.com/
 [readme]: ../readme.md
 [lnk-sdk-vs2015]: http://go.microsoft.com/fwlink/?LinkId=518003
 [lnk-sdk-vs2013]: http://go.microsoft.com/fwlink/?LinkId=323510
 [lnk-sdk-vs2012]: http://go.microsoft.com/fwlink/?LinkId=323511
+[lnk-visualstudio-xamarin]: https://msdn.microsoft.com/en-us/library/mt299001.aspx
+