{"ref":null,"ref_type":"repository","master_branch":"master","description":"Parent class must know its child class and their object in Objective C. Suppose A super class inherited by child class B and B inherited by C, So A want to know that how much classes inherited and their object. In this case A must have object of B & C without knowing the B & C. It does mean we have to keep the object at memory creating of object.","pusher_type":"user"}