Get a list of subclasses of an Objective-C class #advanced #objective-c #runtime #dynamic

objc_get_subclasses.m

+ (NSArray *)subclassesOfClass:(Class)parentClass
{
    int numClasses = objc_getClassList(NULL, 0);
    Class *classes = NULL;
    
    classes = (__unsafe_unretained 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 [NSArray arrayWithArray:result];
}