What causes "unrecognized selector sent to class" error on Xamarin Forms build?

Question

A few things about my system first:

• Mac OS version 10.13.6
• Xcode version 10
• Visual Studio for mac 7.6.6

I'm completely new to Xamarin forms and want to play around and learn. All I'm trying to do is simply create a new xamarin forms solution and get it to build.

Here are the steps I went through:

• create new project
• choose "blank forms app" in C# from the app submenu of multplatform
• target platforms both Andriod and iOs; shared code .NET Standard
• don't bother with version control or app centre test (unticked)

Here is the error:

https://github.com/benfranklin79/shared/blob/master/20180919/error.txt

Here is a link to the solution:

https://github.com/benfranklin79/shared/tree/master/20180919/test

Also here are more detailed visual studio specs

https://github.com/benfranklin79/shared/blob/master/20180919/vs_specs.txt

Answer 1

Whilst this was answered by @snotyak in the comments (and to answer the question in the Answers section), I'm putting this down as an answer.

This seems to have appeared after updating Xamarin.iOS. Xcode requires to install the new components, so all you have to do is open Xcode and let it install the new components.