I have a built C static library (the Antlr 3 C library). It is installed properly and works (i.e., I can run gcc -o parser lexer.c parser.c -lantlr3c just fine).
In Xcode, however, I get an error. I've added -lantlr3c in the "other linker flags" build setting.
ld: library not found for -lantlr3c
Command /Developer/Platforms/iPhoneSimulator.platform/Developer/usr/bin/llvm-gcc-4.2 failed with exit code 1
Several other questions I've found here (1, 2, 3, 4) generally have answers targeting Xcode 3. I'm using Xcode 4.1, in an iOS static library project. I'm currently building the unit test stuff.
EDIT: As requested by @LaceySnr, the output from verbose gcc and Xcode's error.
The output from gcc:
$ gcc -v -o parser.o BFMathParser.c BFMathLexer.c -lantlr3c -arch i386
Using built-in specs.
Target: i686-apple-darwin11
Configured with: /private/var/tmp/llvmgcc42/llvmgcc42-2335.15~25/src/configure --disable-checking --enable-werror --prefix=/Developer/usr/llvm-gcc-4.2 --mandir=/share/man --enable-languages=c,objc,c++,obj-c++ --program-prefix=llvm- --program-transform-name=/^[cg][^.-]*$/s/$/-4.2/ --with-slibdir=/usr/lib --build=i686-apple-darwin11 --enable-llvm=/private/var/tmp/llvmgcc42/llvmgcc42-2335.15~25/dst-llvmCore/Developer/usr/local --program-prefix=i686-apple-darwin11- --host=x86_64-apple-darwin11 --target=i686-apple-darwin11 --with-gxx-include-dir=/usr/include/c++/4.2.1
Thread model: posix
gcc version 4.2.1 (Based on Apple Inc. build 5658) (LLVM build 2335.15.00)
/usr/llvm-gcc-4.2/bin/../libexec/gcc/i686-apple-darwin11/4.2.1/cc1 -quiet -v -iprefix /usr/llvm-gcc-4.2/bin/../lib/gcc/i686-apple-darwin11/4.2.1/ -D__DYNAMIC__ BFMathParser.c -fPIC -quiet -dumpbase BFMathParser.c -mmacosx-version-min=10.7.0 -mtune=core2 -auxbase BFMathParser -version -o /var/folders/5v/9rvx60c17vl7kc3b_r8gz0wc0000gn/T//ccistonB.s
ignoring nonexistent directory "/usr/llvm-gcc-4.2/bin/../lib/gcc/i686-apple-darwin11/4.2.1/../../../../i686-apple-darwin11/include"
ignoring nonexistent directory "/Developer/usr/llvm-gcc-4.2/lib/gcc/i686-apple-darwin11/4.2.1/../../../../i686-apple-darwin11/include"
#include "..." search starts here:
#include <...> search starts here:
/usr/llvm-gcc-4.2/bin/../lib/gcc/i686-apple-darwin11/4.2.1/include
/usr/local/include
/Developer/usr/llvm-gcc-4.2/lib/gcc/i686-apple-darwin11/4.2.1/include
/usr/include
/System/Library/Frameworks (framework directory)
/Library/Frameworks (framework directory)
End of search list.
GNU C version 4.2.1 (Based on Apple Inc. build 5658) (LLVM build 2335.15.00) (i686-apple-darwin11)
compiled by GNU C version 4.2.1 (Based on Apple Inc. build 5658) (LLVM build 2335.15.00).
GGC heuristics: --param ggc-min-expand=150 --param ggc-min-heapsize=131072
Compiler executable checksum: edef36ecca2ce3f93d0f78610b5af911
/usr/llvm-gcc-4.2/bin/../libexec/gcc/i686-apple-darwin11/4.2.1/as -arch i386 -force_cpusubtype_ALL -o /var/folders/5v/9rvx60c17vl7kc3b_r8gz0wc0000gn/T//ccqP9bOO.o /var/folders/5v/9rvx60c17vl7kc3b_r8gz0wc0000gn/T//ccistonB.s
/usr/llvm-gcc-4.2/bin/../libexec/gcc/i686-apple-darwin11/4.2.1/cc1 -quiet -v -iprefix /usr/llvm-gcc-4.2/bin/../lib/gcc/i686-apple-darwin11/4.2.1/ -D__DYNAMIC__ BFMathLexer.c -fPIC -quiet -dumpbase BFMathLexer.c -mmacosx-version-min=10.7.0 -mtune=core2 -auxbase BFMathLexer -version -o /var/folders/5v/9rvx60c17vl7kc3b_r8gz0wc0000gn/T//ccistonB.s
ignoring nonexistent directory "/usr/llvm-gcc-4.2/bin/../lib/gcc/i686-apple-darwin11/4.2.1/../../../../i686-apple-darwin11/include"
ignoring nonexistent directory "/Developer/usr/llvm-gcc-4.2/lib/gcc/i686-apple-darwin11/4.2.1/../../../../i686-apple-darwin11/include"
#include "..." search starts here:
#include <...> search starts here:
/usr/llvm-gcc-4.2/bin/../lib/gcc/i686-apple-darwin11/4.2.1/include
/usr/local/include
/Developer/usr/llvm-gcc-4.2/lib/gcc/i686-apple-darwin11/4.2.1/include
/usr/include
/System/Library/Frameworks (framework directory)
/Library/Frameworks (framework directory)
End of search list.
GNU C version 4.2.1 (Based on Apple Inc. build 5658) (LLVM build 2335.15.00) (i686-apple-darwin11)
compiled by GNU C version 4.2.1 (Based on Apple Inc. build 5658) (LLVM build 2335.15.00).
GGC heuristics: --param ggc-min-expand=150 --param ggc-min-heapsize=131072
Compiler executable checksum: edef36ecca2ce3f93d0f78610b5af911
/usr/llvm-gcc-4.2/bin/../libexec/gcc/i686-apple-darwin11/4.2.1/as -arch i386 -force_cpusubtype_ALL -o /var/folders/5v/9rvx60c17vl7kc3b_r8gz0wc0000gn/T//ccepo2q0.o /var/folders/5v/9rvx60c17vl7kc3b_r8gz0wc0000gn/T//ccistonB.s
/usr/llvm-gcc-4.2/bin/../libexec/gcc/i686-apple-darwin11/4.2.1/collect2 -dynamic -arch i386 -macosx_version_min 10.7.0 -weak_reference_mismatches non-weak -o parser.o -lcrt1.10.6.o -L/usr/lib/i686-apple-darwin11/4.2.1 -L/usr/llvm-gcc-4.2/bin/../lib/gcc/i686-apple-darwin11/4.2.1 -L/usr/llvm-gcc-4.2/bin/../lib/gcc -L/Developer/usr/llvm-gcc-4.2/lib/gcc/i686-apple-darwin11/4.2.1 -L/usr/lib/gcc/i686-apple-darwin11/4.2.1 -L/usr/llvm-gcc-4.2/bin/../lib/gcc/i686-apple-darwin11/4.2.1/../../.. -L/Developer/usr/llvm-gcc-4.2/lib/gcc/i686-apple-darwin11/4.2.1/../../.. /var/folders/5v/9rvx60c17vl7kc3b_r8gz0wc0000gn/T//ccqP9bOO.o /var/folders/5v/9rvx60c17vl7kc3b_r8gz0wc0000gn/T//ccepo2q0.o -lantlr3c -lSystem -lgcc -lSystem
The output from Xcode:
Libtool /Users/bf/Library/Developer/Xcode/DerivedData/Calculator-dggaoccanosfnrampxhlfrbuuyoi/Build/Products/Debug-iphonesimulator/libcalclib.a normal i386
cd /Users/bf/Desktop/calclib
setenv MACOSX_DEPLOYMENT_TARGET 10.6
setenv PATH "/Developer/Platforms/iPhoneSimulator.platform/Developer/usr/bin:/Developer/usr/bin:/usr/bin:/bin:/usr/sbin:/sbin"
/Developer/Platforms/iPhoneSimulator.platform/Developer/usr/bin/libtool -static -arch_only i386 -syslibroot /Developer/Platforms/iPhoneSimulator.platform/Developer/SDKs/iPhoneSimulator4.3.sdk -L/Users/bf/Library/Developer/Xcode/DerivedData/Calculator-dggaoccanosfnrampxhlfrbuuyoi/Build/Products/Debug-iphonesimulator -filelist /Users/bf/Library/Developer/Xcode/DerivedData/Calculator-dggaoccanosfnrampxhlfrbuuyoi/Build/Intermediates/calclib.build/Debug-iphonesimulator/calclib.build/Objects-normal/i386/calclib.LinkFileList -lantlr3c -ObjC -framework Foundation -o /Users/bf/Library/Developer/Xcode/DerivedData/Calculator-dggaoccanosfnrampxhlfrbuuyoi/Build/Products/Debug-iphonesimulator/libcalclib.a
Command /Developer/Platforms/iPhoneSimulator.platform/Developer/usr/bin/libtool failed with exit code 1
Click your project in the navigator, select the appropriate target, and unfold the Linked Frameworks and Libraries section. Click the plus, click Add Other..., and browse to your static object.
You'll have to remove the -lantlr3c flag too.
You can use that in the other linker flags, but you also need to make sure the path is in the library search paths too.
Also make sure you're building with the right config (debug / release / whatever) — you can specify different libraries to link for each one, so if you've set it for debug but you're building release it obviously won't link.
When you test this lib with gcc on your Mac you are using the x86 version of it. The iOS linker does not find it because you probably did not build the arm version of the library.
来源：https://stackoverflow.com/questions/7605805/including-external-c-library-with-xcode