Integration of Developed Unity App into another developed Native iOS app as part of application by adding subview or any other way?

I want to integrate developed Unity app into one controller of another existing native iOS app as part of application. Can you suggest me which approach will be more easy and helpful. I already tried to add static classes and library of unity app into actual Native iOS app but it is very lengthy and complex process. Can i do integration using pod of developed unity app? is there any way? Kindly Help?