Objective-C equivalent of Java packages?

Question

What is the Objective-C equivalent of Java packages? How do you group and organize your classes in Objective-C?

Answer 1

Well, I think all the other answers here seem to focus on naming collisions, but missed at least one important feature, package private access control that java package provides.

When I design a class, I find it is quite often that I just want some specific class(es) to call its methods, b/c they work together to achieve a task, but I don't want all the other unrelated classes to call those methods. That is where java package access control comes in handy, so I can group the related classes into a packaged and make those methods package private access control. But there is no way to do that in objective c.

Without package private access control I find it is very hard to avoid people writing code like this, [[[[[a m1] m2] m3] m4] m5] or [a.b.c.d m1].

Update: Xcode 4.4 introduced "An Objective-C class extension header", in my opinion, that is in some way to provide "package private access control", so if you include the extension header, you can call my "package private" methods; if you only include my public header, you can only call my public API.