How to merge Unity Xcode Project to iOS Xcode Project?

Hello, I am trying to launch unity game from iOS application with button click, I have iOS application which made in Xcode and from that application UI button want to launch unity app/game. But don't know how it is possible to do. I tried from following link- but it is getting linking error **http://alexanderwong.me/post/29949258838/building-a-ios-unity-uiview-uiviewcontroller**