Question

I have an NSArray arr. It has a bunch of NSNumber objects. I’m trying to calculate statistics analysis on the array using GNU’s GSL. GSL takes parameters as C-style arrays.

Is there any mechanism that can, for example, run ‘intValue’ on all of the objects in a NSArray object, and convert the results that to a C-style array?

I don’t really want to copy the contents of the NSArray to a C-style array, as it’s a waste of space and cycles, so I’m looking for an alternative.

Answer 1

The mechanism you’re describing — run intValue on all the objects in the NSArray and give a C-style array — seems to be exactly the same thing you describe as “a waste of space and cycles.” It’s also the only real way to do this if you need a C-style array of ints. Best approach I can think of:

int *c_array = malloc(sizeof(int) * [yourArray count]);
[yourArray enumerateObjectsWithOptions:NSEnumerationConcurrent 
                            usingBlock:^(id number, NSUInteger index, BOOL *unused) {
    c_array[index] = [number intValue];
}];