Determining the number of available cores on a machine?

Question

I want my software to create one thread per core, obviously different Macs have a different number of cores.

Does anyone know how to (programmatically, via Cocoa) determine the number of cores?

Answer 1

See How do I detect a dual core CPU on iOS? It works in OS X too.

unsigned int countCores()
{
    size_t len;
    unsigned int ncpu;
    len = sizeof(ncpu);
    sysctlbyname ("hw.ncpu",&ncpu,&len,NULL,0);
    return ncpu;
}

Answer 2

[[NSProcessInfo processInfo] processorCount]