xcode - Compile C lib for iPhone

Question

I'm trying to compile ZeroMQ C binding in order to be able to use it on iPhone, here is my configure options:

./configure --host=arm-apple-darwin --enable-static=yes --enable-shared=no CC=/Developer/Platforms/iPhoneOS.platform/Developer/usr/bin/arm-apple-darwin10-gcc-4.2.1 CFLAGS="-pipe -std=c99 -Wno-trigraphs -fpascal-strings -O0 -Wreturn-type -Wunused-variable -fmessage-length=0 -fvisibility=hidden -miphoneos-version-min=3.1.2 -gdwarf-2 -mthumb -I/Library/iPhone/include -isysroot /Developer/Platforms/iPhoneOS.platform/Developer/SDKs/iPhoneOS4.0.sdk -mdynamic-no-pic" CPP=/Developer/Platforms/iPhoneOS.platform/Developer/usr/bin/cpp AR=/Developer/Platforms/iPhoneOS.platform/Developer/usr/bin/ar AS=/Developer/Platforms/iPhoneOS.platform/Developer/usr/bin/as LIBTOOL=/Developer/Platforms/iPhoneOS.platform/Developer/usr/bin/libtool STRIP=/Developer/Platforms/iPhoneOS.platform/Developer/usr/bin/strip RANLIB=/Developer/Platforms/iPhoneOS.platform/Developer/usr/bin/ranlib

It actually configures and compiles fine, but when I add it to Xcode Frameworks section, I get warning: ld: warning: in /path/to/app/libzmq.a, file was built for unsupported file format which is not the architecture being linked (armv7) and a lot of symbol not found errors.

If I change current active architecture from armv6 to armv7, warning message will change it to armv6. What am I doing wrong ?

Thanks, Dan

Answer 1

It sounds like you're building a universal armv6/armv7 binary for the iPhone (this is the default, so that makes sense). That means that you need to build a universal library to link against. Build both libraries, and then use lipo to combine the two.

For example, build the armv6 one and place it at armv6/libfoo.a, and the armv7 one at armv7/libfoo.a. Then run

lipo -arch armv6 armv6/libfoo.a -arch armv7 armv7/libfoo.a -output libfoo.a -create

to create the universal library libfoo.a.