Unfortunately apple has not included header files for libicucore on OSX. Is there any way I can nevertheless use this library? I only need some simple functionality and ICU is too big to bundle with my app. It looks like ICU version 53.1.0 which is fairly recent:
jeroen$ otool -L /usr/lib/libicucore.dylib
libicucore.dylib:
/usr/lib/libicucore.A.dylib (compatibility version 1.0.0, current version 53.1.0)
/usr/lib/libc++.1.dylib (compatibility version 1.0.0, current version 120.0.0)
/usr/lib/libSystem.B.dylib (compatibility version 1.0.0, current version 1213.0.0)
What complicates things is that I have a hard time finding out what is included with the core target of ICU. I can use nm to manually check if a particular symbol is present in the library:
jeroen$ nm /usr/lib/libicucore.dylib | grep ToUpper
00000000000b74c9 T _u_strToUpper
000000000006ff70 T _ucasemap_utf8ToUpper
Now I can manually grab the headers for u_strToUpper from the 53.1.0 release of ICU, but that is a lot of work. Is there a better way to find or generate the headers for ICU core 53.1.0 on OSX?
You can download header files from Apple's website or from ICU official website and link against system's libicucore library.
But you can't upload a product to App Store or Mac App Store. It will be immediately rejected as one that uses private API. iTunes Connect has automatic script that detects such references after you upload new binary.
It looks like my best bet is grabbing the headers from the apple website. This repository also includes the makefile for libicucore.dylib which uses --with-data-packaging=archive to put the ICU data tables in a standalone file /usr/share/icu/icudt51l.dat.