在cocoa(或objective C)中，是否有方法向另一个进程中的对象发送消息?

Let's say I have two Cocoa apps running on the same machine (OSX). Is there a way to send "objective c" messages from one to objects in the other one? These two apps need to remain independent, so they can be started and stopped by the user independently or users can have only one of the two on their machines. I know the best solution maybe using Sockets or pipes, but I wanted to know if I am not instantiating an object is there a way to send it a message (or call its methods) in anyway? I understand that the receiver may just ignore the messages or does whatever it wants with them.Let's say I have two Cocoa apps running on the