➜ ~ ls -la /usr/local/opt/json-c/lib/
total 184
drwxr-xr-x 6 oleg admin 192 Jun 7 2016 .
drwxr-xr-x 12 oleg admin 384 Jan 5 15:14 ..
-r--r--r-- 1 oleg admin 37364 Jan 5 15:14 libjson-c.2.dylib
-r--r--r-- 1 oleg admin 50376 Jun 7 2016 libjson-c.a
lrwxr-xr-x 1 oleg admin 17 Jun 7 2016 libjson-c.dylib -> libjson-c.2.dylib
drwxr-xr-x 3 oleg admin 96 Jan 5 15:14 pkgconfig
➜ ~
Вот здесь находится либа.
LIBS += -L/usr/local/opt/json-c/ -ljson-c
