How to implement nested classes in objective-c like Java?

Question

I need to implement nested classes. How do I write it in objective-c?
For example, I have such code:

public class A {
    private int a;
    private B b;

    class B {
        private int z;
        public void f() {
            a = 1;
        }
    }

    public void fA() {
        b.f();
    }
}

How can I implement this code in objective-c??

Solution

From my understanding, Objective-C doesn't have inner classes.. Try these links where this question has been asked before:

How to access a variable from inner class

Private classes in Objective C

http://lists.apple.com/archives/objc-language/2004/Dec/msg00041.html