Using iterateFunc to call objective c method - objective-c

Question

Using spacemanager, I need to perform an action on select bodies after each step, so I figured that defining my own C function for iterateFunc would be the way to go.
Everything works great, except I'm not sure how to then call an obj c method in the same class. In other words, an obj c class contains both the c function replacing iterateFunc, and the method that needs to be called. I don't see how to tell the c function what 'self' is, such that I can call the method. As far as i can tell, there's no way to pass in any extra info to the new iterateFunc.
Any ideas, or a better way to go about things?
Update:
Thanks for the response. Declaring a new spacemanager, one can redefine its iterateFunc:
smgr = [[SpaceManager alloc] init];
smgr.iterateFunc=doThisFunc;
In the same class, a "doThisFunc" function can be declared.
In spacemanager, this iterateFunc is called from the "step" method:
-(void) step: (cpFloat) delta
{
.....
cpSpaceHashEach(_space->activeShapes, _iterateFunc, self);
....
}
So my first thought was to subclass spacemanager, and in my custom step method, call cpSpaceHashEach with my own class, instead of self (the spacemanager, that is). Halfway there, I realized that I didn't even have to do that, as subclassing and defining my own step method was all I needed to do. My new step method:
-(void) step: (cpFloat) delta
{
[super step:delta];
//Having of course set the "myObject" variable elsewhere as my other object
[myObject doThis];
}
Thanks, bbum for both your answers, and for helping me craft better questions in the future.

Answer 1

Holy vagueness, batman, where's the code snippet? Thankfully, the Magic Powers of Google save the day.
To answer this question requires a few bits of detail:
What is the declaration of iterateFunc?
Oh. It is a cpSpaceHashIterator. Not helpful.
Ah... there it is:
typedef void (*cpSpaceHashIterator)(void *obj, void *data);
It looks like the void *data argument is your answer. Specifically, it looks like that is passed through transparently to your iterator function. That is, if you call:
cpSpaceEachBody(cpSpace *space, cpSpaceBodyIterator func, void *data)
Like this:
cpSpaceEachBody(space, funcPtr, (void *)self);
Then your iterator func could do this:
void iteratorFunc(void *obj, void *data) {
[(MyClass *)data iterateThis: obj];
}