So after upgrading XCode, my app no longer compiled and kept giving me this message:
"Unsupported compiler 'GCC 4.2' selected for architecture 'i386'"
To fix it:
1. Click on your project in the 'project' menu.
2. Click on 'build settings'
3. Look for GCC_VERSION, under 'Build Options'
4. Change your GCC_VERSION to 'Any SDK'
The project should compile now.
See this screenshot for what I mean: