Xcode Version 6.1 (6A1030) - Apple Mach O-Linker Error - Building
As usual when upgrading Xcode:
- Clean your build folder (Product -> (Alt key) -> Clean Build Folder)
- Clean project (Product -> Clean)
- Delete derived data
- Xcode < 6.3: Window -> Organizer -> Delete derived data
- Xcode >= 6.3: Window -> Projects (select project) -> Delete derived data
Then try to build your project again.