Undefined symbols for architecture arm64: "_OBJC_CLASS_$_P31MonoBridge"

While building my xCode project from Unity, I am getting this kind of error as result when I try to build a project. I have added only one plugin - GameKit and that is very old that I know but any how I want to use this plugin because I don't have latest version of it. My xCode version is 7.0.1 and Unity version is 4.6.3.

Here I am attaching screenshots for give you more idea about error I am getting.

Architectures Section :

View attachment 160446

Debug Section :...

Undefined symbols for architecture arm64: "_OBJC_CLASS_$_P31MonoBridge"