Error in xcode project: ld: library not found for -lcrt1.10.6.o

Question

Edit Project Settings -> In the build tab -> For Mac OS X Deployment Target, change it to 10.5 for XCode 3 (not 10.6 even if on 10.6) and see if that helps.

For XCode 4, you'll need to set it to 10.6

P.S. Make sure you set that for all targets, not just release or debug. (if you didn't, one would fail, the other wouldn't)

Add the following to ~/.profile (for Mac OS X 10.5):

export C_INCLUDE_PATH=/Developer/SDKs/MacOSX10.5.sdk/usr/include
export LIBRARY_PATH=/Developer/SDKs/MacOSX10.5.sdk/usr/lib

I was able to fix this problem by adding the following to my Makefile:

CFLAGS="$(OTHER_CFLAGS) -mmacosx-version-min=10.5"
LDFLAGS="$(OTHER_LDFLAGS) -mmacosx-version-min=10.5"

Ostensibly, this is only required when building outside of Xcode. This problem frustrated me long enough that I figured it would be useful to share my experience here.

It looks like you're picking up libraries from /usr/lib, which is wholly inappropriate for the iPhone SDK. I would assume you've changed your build settings to add /usr/lib to the library search paths. This should be completely unnecessary in the first place, as /usr/lib is in the compiler's standard search paths, but if you need to have a modified search path like this, make sure to use $(SDKROOT)/usr/lib instead.