I have an app that runs great in Xcode 5, using CocoaPods.
When I open the app on Xcode 6 and hit build and run, I get four errors from the FiksuSDK about compiled n
This isn't a very good answer, but I had this same problem and in order to keep developing (until this gets figured out), I just removed those 4 nibs from the project. Just go to the project file, select the target you're building against, go to the "Build Phases" tab, and delete those 4 nibs from the "Copy Bundle Resources" section. Your project should build and run fine for the time being (I haven't encountered any negative effects to not having these nibs). By the way I think they're from the Fiksu SDK, not the Facebook SDK.