Xamarin.iOS

Xamarin.iOS is used for building applications for iOS with .NET, and contains the bindings to the iOS APIs mentioned previously. Xamarin.iOS uses ahead of time (AOT) compiling to compile the C# code to Advanced RISC Machines (ARM) assembly language. The Mono runtime runs along with the Objective-C runtime. Code that uses .NET namespaces, such as System.Linq or System.Net, will be executed by the Mono runtime, while code that uses iOS-specific namespaces will be executed by the Objective-C runtime. Both the Mono runtime and the Objective-C runtime will run on top of the Unix-like kernel, X is Not Unix (XNU) (https://en.wikipedia.org/wiki/XNU), which is developed by Apple. The following diagram shows an overview of the iOS architecture: