Telerik offers Xamarin.iOS wrappers on top of the native UI for iOS suite. The controls, features and API that are available in UI for iOS are available in the Xamarin.iOS wrappers in a C# form*. These wrappers are not included in the UI for iOS product, but are offered separately as a part of UI for Xamarin.iOS or UI for Xamarin Cross-Platform products.
Since the API and scenarios of the Telerik Xamarin.iOS wrappers strictly follow those of the native Telerik UI for iOS controls, the documentation for UI for iOS is also a valid documentation for UI for Xamarin.iOS. For every feature where an Objective-C/Swift code snippet is included, you can also find a C# code snippet that shows how something can be achieved with the Xamarin.iOS wrappers.
You can learn more about the underlying UI for iOS product and controls from the UI for iOS Overview page.
To get started with the Telerik Xamarin.iOS wrappers, check the common Getting Started with Xamarin.iOS article article that is valid for all Telerik Xamarin.iOS controls.
Note: There could be information for more controls in the UI for iOS suite that what is supported for the Xamarin.iOS wrappers. For a list of the supported Xamarin.iOS controls, you can refer to the UI for Xamarin product page.