While I applaud the effort, why on earth would anyone write a numerical library in obj-c? AFAIK, there aren't any platforms that support obj-c but not C/C++.
I need stuff like this from time to time, but I wouldn't restrict my portability like this unless I really had to.
Presumably it's because the author is comfortable in the language, it's capable of doing what he needs, and runs on the platforms where he intends to use it.
I mean, seriously. Are you going to crap all over this project just because it's not in your language of choice? What's your standard for a project that can legitimately use ObjC? C can do everything ObjC can do, after all, if you try hard enough.
Because Accelerate framework is in obj-c? (It is in C).
But in all seriousness, most cases, you want to implement your own neural network anyway because the specific choice of network structure, activation functions etc. Beyond that, it just matrix multiplication which is well handled by lower level primitives like libatlas / libcblas / CUDAblas etc.
I wrote it for real time motion analysis. Since it requires some signal processing and detection, I decided to use Accelerate framework. Though my main tool is R for such things.
If you read the code, you'll see that it's mostly C wrapped in Obj-C methods. It also uses the Accelerate.framework (which is optimised to the hilt and very fast) for matrix multiplication.
I need stuff like this from time to time, but I wouldn't restrict my portability like this unless I really had to.