iPhone Objective-C foreach design

Question

I\'m trying to implement a design as follows:

Touch class : acts as an interface, several classes inherit from it:
MoveTouch class

Answer 1

You need to test for the class type:

for (Touch *t in touches) {
  if ([t isKindOfClass:[MoveTouch class]]) {
    MoveTouch *mt = (MoveTouch *)t;
    // do what you want with mt
  }
}

Answer 2

I'm not an Objective C programmer.

In your case, I think you need to go through your list with that "for (Touch* in touches)" and in the body figure out if that object is either a MoveTouch or a JumpTouch and so forth.

But the idea of polymorphism is that you don't do this. You don't sort 'm out during your loop. The action that you want to perform should be defined in the interface, and each descendant class implements a different implementation for that action. That's what polymorphism is all about.