This kept happening to me: perfect code that compiled before doesn’t even compile now. Any project.
A major shitstorm.
ld: in /Applications/Xcode.app/Contents/Developer/Platforms/iPhoneSimulator.platform/Developer/SDKs/iPhoneSimulator6.0.sdk/usr/lib/system/libsystemsimm.dylib, can't open file, errno=-22 for architecture i386
Turns out that an update of the Command Line Tools that popped on my Xcode was one for version 4.5.1 but the update wasn’t still pushed to the Mac App Store. Waiting and installing it solved the problem.
Still, what a hard time it gave me.