How to add some of App Extensions to Unity ios build

Really, how to do it?

I want to use, for example, Today Extension for my ios app made in unity. When open my app in Xcode and try to do it with File -> New -> Target -> Application Extension -> Today Extension, I get an error about some missing file.

Do I need some special way of adding these app extensions or I am doing something fundamentally wrong.
Is it still not compatible even though unity did made ios 8.1 build available?
Can this be done, or not?

Please, give me some answers,...

How to add some of App Extensions to Unity ios build