Interface Builder XIB compiler error on Xcode 8

Click on your .XIB file 

From Right side bar select "Show the file Inspector"

Go to "Interface Builder Document" section.

In "Open In" dropdown select Xcode 8.

Clear derived data, Build and Run. 

May this help you.

I have solved this issue by following below steps:

1. cmd + shift + k
2. cmd + option + shift + k
3. Restart Xcode
4. Restart your pc.

Hope this will also works for you. Thanks!