Type register and method export attributes for objc in Rust like C# in xamarin? #56

It is very convenient to expose a C# class to objc by using attributes. (Usage: https://developer.xamarin.com/guides/ios/advanced_topics/registrar/ Implement: https://github.com/mono/cocoa-sharp/) .

Rust has the same attribute system like C#. So is it possible to have these attributes in Rust?

One of the benefits or needs is to use solid type instead of marked type connect between Rust and objc, and to wrap Rust struct method instead of static method for objc message receiving.

cocoa-sharp has these tricks.