get subclasses

gistfile1.m

#import <objc/runtime.h>

NSArray* ClassGetSubclasses(Class parentClass)
{
    int numClasses = objc_getClassList(NULL, 0);
    Class *classes = NULL;

    classes = (Class*)malloc(sizeof(Class) * numClasses);
    numClasses = objc_getClassList(classes, numClasses);

    NSMutableArray *result = [NSMutableArray array];
    for (NSInteger i = 0; i < numClasses; i++)
    {
        Class superClass = classes[i];
        do
        {
	  superClass = class_getSuperclass(superClass);
        } while(superClass && superClass != parentClass);

        if (superClass == nil)
        {
            continue;
        }

        [result addObject:classes[i]];
    }

    free(classes);

    return result;
}