Measure memory usage of a process in Cocoa/Objective-C?

I want to make a program that is able to show the amount of RAM that Google Chrome uses. Chrome uses a process for each tab and each plug-in/extension (basically), so you can't know with a glance on the a开发者_运维问答ctivity monitor the amount of RAM it's taking.

My idea was to give the program the name of the process (Chrome), and it will search every child process. I will add then the amount of memory taken by all the parented process to have my answer.

The problem is: I can't find a class that can give me the amount of memory taken by a process.

I've find a way to get the PID from the name of the app (and vice versa) with the sample code PIDFromBSDProcessName written in C. But I can't find the memory, neither in NSRunningApplication, NSTask of NSWorkSpace classes.

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One problem is that there will likely be some shared memory between the various processes that an application will find very hard to detect. Also if it maps a file like the bookmarks/history DBs into memory as well that will appear as if it were normal memory, making a tool like this very inaccurate.