Why getting differences between using XCode and xcodebuild?

Question

Can anyone explain why I get different results when compiling the same XCode 4.x project using the GUI and xcodebuild command-line?

XCode GUI

1. Perform a clean
2. Build "Release" target
3. Build successfully

xcodebuild

1. Perform a clean
2. Run "xcodebuild -configuration Release"

3. Results in the following errors:

   /Developer/usr/bin/gcc-4.0 -x objective-c -arch i386 -fmessage-length=0 -pipe -std=gnu99 -Wno-trigraphs -fpascal-strings -fasm-blocks -Os -Wreturn-type -Wunused-variable -isysroot /Developer/SDKs/MacOSX10.4u.sdk -fvisibility=hidden -mmacosx-version-min=10.4 -c "/Users/XXX/Extensions/NSFileManager_Extensions.m" -o "/Users/XXX/Developer/Intermediates/YourApp.build/Release/YourApp.build/Objects-normal/ppc/NSFileManager_Extensions.o" /Users/XXX/Extensions/NSFileManager_Extensions.m:15:60: error: ToxicRegularExpressions/ToxicRegularExpressions.h: No such file or directory ** BUILD FAILED **

The following build commands failed: CompileC "/Users/XXX/Developer/Intermediates/YourApp.build/Release/YourApp.build/Objects-normal/ppc/NSFileManager_Extensions.o" /Users/XXX/Extensions/NSFileManager_Extensions.m normal ppc objective-c com.apple.compilers.gcc.4_0

And finally GUI + xcodebuild

1. Perform a clean in GUI
2. Build "Release" target
3. Builds successfully
4. Run "xcodebuild -configuration Release"
5. Builds successfully

Answer 1

Try passing the SDK on the command line, like so:

xcodebuild -configuration Release -sdk iphonesimulator3.0