Hack a .a library file

gistfile1.sh

# Using libtool, lipo, ar and otool

lipo -info input.a

lipo -extract_family arm64 -output output.a input.a

# output.a is a fat file (use libtool(1) or lipo(1) and ar(1) on it)
# lipo output.a -thin arm64 -output output_arm64.a

ar -x output_arm64.a

otool -tv xxx.o

libtool -static -o output_arm64_new.a *.o

lipo -create -output lib.a output_arm64_new.a output_armv7s_new.a output_armv7_new.a output_i386_new.a