Question

This is ONLY regarding the new Xcode 4.1, specifically running on Lion. How do you enable NSZombie in Instruments ? It is no longer in Allocations in the (i) icon under Launch Configuration as in Xcode 4.0. Nor is there a Library entry called Zombies.

Of course the problem is I cannot fall back to Xcode 4.0 because it refuses to run under Lion, so I’m in a pickle ! Any other bleeding edge developers using Lion who, with more experience than myself, can help dig this out ? Thanks. -Ric

Answer 1

I got this very useful answer from Apple regarding my own question. It is verbatim –

ME: Is there an update as to how to find those tough deallocated objects, testing on the device, using Xcode 4.1.1 and/or Instruments ?

APPLE: First up, the hack shown above [in Apple’s Forum] has been obsoleted by internal changes to the OS, namely, Zombie setup is now done by CF. You can force zombies enabled using the code shown below:

extern void _CFEnableZombies(void);

int main(int argc, char **argv)
{
_CFEnableZombies();

... rest of your main ...

}

IMPORTANT: The _CFEnableZombies function is private, so you don’t even think about putting this code into a production app. However, it’s not secret; you can see how it’s implemented by looking in the Darwin open source for Lion.

http://www.opensource.apple.com/source/CF/CF-635/CFRuntime.c

If you do this, your app will stop (with a breakpoint exception) when you message a zombie, regardless of how you run it. So you can run it in Instruments with the Allocations instrument and get both zombie detection and allocation tracking.

Note that when a zombie is messaged the system prints something like this:

*** -[ ]: message sent to deallocated instance “

This doesn’t appear in the Instruments console area; you’ll have to use the Xcode Organizer (or iPCU) to view it.

Share and Enjoy

Quinn “The Eskimo!”
Apple Developer Relations, Developer Technical Support, Core OS/Hardware

ME: hope that is useful info for some of you in this situation.