I have just migrated to Xcode 4 and i had zombie activated in Xcode 3 for my app. I used the following method:
Go to Project -> Edit Active Executable Click Arguments Click + in the "Variables to be set in the environment" section Enter NSZombieEnabled in the Name column and YES in the Value column. Make sure the checkmark for the NSZombieEnabled entry is checked.
Now i want to make sure it is off for my application but do not understand how to check/do that in XCODE4, anyone that can share some light on that?
To edit environment variables, go to Menu Product / Edit Scheme…, select the desired configuration (you probably want 'Run') from the left sidebar first and then click on the Arguments tab. Environment variables are configurable there.
来源：https://stackoverflow.com/questions/5810931/how-to-turn-off-nszombieenabled-in-xcode-4