After updating to XCode 7.1.x on El Capitan I was unable to build a MarvelApp export from our design agency. Despite nothing having changed with the code and nothing else obvious I assumed that XCode must've broke something on update.
As with most things XCode related this theory is correct. To fix navigate over to the Search Paths within the Build settings and add the following:
After that you should be all good. I'm sure there is a well meant reasoning behind this - my XCode knowledge is patchy right now - but I can't exactly say this is intuitive.