After updating to Xamarin.iOS 7.2.1 this morning, I can no longer build my project. It includes references to Stampsy.Social, as well as modified versions of the Xamarin.Auth and Xamarin.Social libraries that are required by it, given to me by @DanAbramov some time ago. Up until now I've had no issues, but 7.2.1 introduced the following error:
error MT4116: Could not register the assembly 'Xamarin.Auth.iOS': Error MT4118: Cannot register two managed types ('Xamarin.Controls.ProgressLabel, Xamarin.Auth.iOS, Version=1.1.0.0, Culture=neutral, PublicKeyToken=null' and 'Xamarin.Controls.ProgressLabel, Xamarin.Social.iOS, Version=1.0.2.0, Culture=neutral, PublicKeyToken=null') with the same native name ('Xamarin_Controls_ProgressLabel'). (MT4118)
Looking through the assembly browser, it appears that both the Xamarin.Auth and Xamarin.Social libraries define a class ProgressLabel which extends UIView, and the new registrars (which I had never used until 7.2.1 when they were enabled by default) doesn't seem to like these two classes having the same name when they're compiled to native code.
A workaround is to use the legacy registrars, as discussed in the release notes, by adding the --registrar:legacy additional mtouch argument. Of course, I would prefer not to do this as there are many benefits to using the new registrars.