I just updated to Xcode version 4.6.2 (4H10003) and tried to run a previously working application project in the simulator and received the following error and the build fai
From XCode 4.6.2 Release Notes
Known Issues
Building
When building a product previously built with Xcode 4.6.1 or earlier, the build fails with an error similar to this one:
PCH file built from a different branch ((clang-425.0.27)) than the compiler ((clang-425.0.28))
To address this issue, choose Product > Clean before building your product. 13663167
Performing Product > Clean works