Will Need:
1. Mac running OSX 10
2. Install latest version of Apple’s Developer Tools / Xcode
https://developer.apple.com/technologies/tools/
3. Once installed, in Xcode go to “XCode”–>”Preferences”–>”Downloads” and install “Command Line Tools” (will need this if you want to “make” any bindings to additional Objective-C components).
4. Download and install MonoTouch. This will include: 1) Mono, an open source .NET implementation; 2) MonoDevelop, an open source IDE similar to Visual Studio; and, 3) MonoTouch, the proprietary set of libraries that allow you to compile C# code into iOS apps.
5. Your now ready to do the first tutorials found here:
http://docs.xamarin.com/ios
To this point you can write code and run it in the simulator.
To actually deploy it to a device you will need a licensed copy of Monotouch and one of the following:
Apple Developer Program ($99 a year) – provision ad-hoc deployment on up to 100 different devices for testing and distribute/sell apps via app store.
https://developer.apple.com/programs/ios/
Apple Enterprise Program ($299 a year) – deploy .ipa bundled apps to corporate owned or corporate employee owned devices.