ObjFW is a portable, lightweight framework for the Objective-C language. It enables you to write an application in Objective-C that will run on any platform supported by ObjFW without having to worry about differences between operating systems or various frameworks you would otherwise need if you want to be portable.
It supports all modern Objective-C features when using Clang, but is also compatible with GCC ≥ 4.6 to allow maximum portability.
ObjFW version 1.0 has just been released, which is, of course, a major milestone for any project. In this case, it also means ObjFW now has a stable API and ABI. ObjFW is available on a variety of platforms, from macOS and Windows to more exotic ones like the Amiga and Nintendo (3)DS.
The license is a non starter for most stuff.
It’s available under 3 different licenses. Undoubtedly, one of those licenses will be acceptable for pretty much every one who wants to use it.