Xamarin has integrated its cross-platform development tools with Microsoft’s Visual Studio Community 2013, allowing developers to build native Android and iOS apps for free.

The (just released yesterday) Visual Studio 2015 Update 2 installer will install Xamarin for you (it's one of several checkboxes under Cross-Platform Development), and IIRC will install it by ...

Like a mobile force, Xamarin 4 awakens. So upgrade now, especially if you're a Visual Studio developer and building apps for iOS.