How to enable NSZombie in Xcode?

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I have an app that is crashing with no error tracing. I can see part of what is going on if I debug, but can't figure out which object is "zombie-ing".

Does anybody know how to enable NSZombie in Xcode 4?

Tardiff answered 22/3, 2011 at 2:44 Comment(0)

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Environment variables are now part of the "scheme".

To edit the scheme and turn on zombies:

In the "Product" menu, select "Scheme" > "Edit Scheme...".
Go to the "Run Foo.app" stage in the left panel, and the "Arguments" tab on the right.
Add NSZombieEnabled to the "Environment Variables" section and set the value to YES, as you could in Xcode 3.

In Xcode 4.1 and above, there's also a checkbox on the "Diagnostics" tab of the "Run" stage to "Enable Zombie Objects".

With Xcode 6.4:

Juxon answered 22/3, 2011 at 4:57 Comment(5)

Doesnt break on the call to the deallocated object on device, any way to make that happen? – Untouchable 21/10, 2011 at 15:31

It changed again in 4.2, see my answer below. Go to Product->Edit Scheme->Diagnostics – Logy 16/11, 2011 at 12:29

In Xcode, in the Help menu at the top (last one on the right) search for "Edit Scheme" it will point you in the right direction every time in any version. – Peppery 3/3, 2014 at 21:16

If we enable this NSZombieEnabled feature to our app shall we release the app to store..? Because I saw one post saying that its not good practice to release to store when we enable this feature. – Oddson 24/2, 2015 at 10:14

For the rookies coming after, in Xcode 6.1 you go menu Product> Scheme-Edit Scheme>Diagnostics tab>Checkbox Enable Zombie Objects – Antagonize 3/3, 2015 at 17:49

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I encountered the same problem with troubleshooting EXC_BAD_ACCESS and had hard time to find the setting with Xcode 4.2 (the latest one that comes with iOS5 SDK). Apple keeps on moving things and the settings are no longer where they used to be.

Fortunately, I've found it and it works for the device, not just Simulator. You need to open the Product menu in the Xcode, select Edit scheme and then choose the Diagnostics tab. There you have "Enable Zombie Objects". Once selected and run in debugger will point you to the double released object! Enjoy!

In short

Product->Edit Scheme->Diagnostics-> Click Enable Zombie Objects

Logy answered 16/11, 2011 at 12:28 Comment(1)

In Xcode, in the Help menu at the top (last one on the right) search for "Edit Scheme" it will point you in the right direction every time in any version. – Peppery 3/3, 2014 at 21:16

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Product > Profile will launch Instruments and then you there should be a "Trace Template" named "Zombies". However this trace template is only available if the current build destination is the simulator - it will not be available if you have the destination set to your iOS device.

Also another thing to note is that there is no actual Zombies instrument in the instrument library. The zombies trace template actually consists of the Allocations instrument with the "Enable NSZombie detection" launch configuration set.

Alexandra answered 5/5, 2011 at 1:19 Comment(2)

"However this trace template is only available if the current build destination is the simulator". Thank you! – Microphyte 24/8, 2011 at 12:19

In Xcode, in the Help menu at the top (last one on the right) search for "Edit Scheme" it will point you in the right direction every time in any version. – Peppery 3/3, 2014 at 21:17

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It's a simple matter of setting an environment variable on your executable (NSZombieEnabled = YES), and then running/debugging your app as normal.If you message a zombie, your app will crash/break to debugger and NSLog a message for you.

For more information, check out this CocoaDev page: http://www.cocoadev.com/index.pl?NSZombieEnabled

Also, this process will become much easier with the release of 10.6 and the next versions of Xcode and Instruments. Just saying'. =)

Stethoscope answered 31/7, 2009 at 15:16 Comment(1)

Totally agreed. The new Zombies instrument is very nice. – Benson 2/8, 2009 at 15:9

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Product > Profile will pop up Instruments. Select zombies from the panel and go nuts.

Liturgics answered 4/4, 2011 at 13:56 Comment(1)

@jluebbert I'd say try harder because I definitely see it, running Xcode 4.02 – Liturgics 3/5, 2011 at 2:32

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Go to Product - Scheme - edit scheme - Arguments - Environment Variables set NSZombieEnabled = YES

enter image description here

Cantabrigian answered 11/12, 2013 at 9:48 Comment(0)

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In xcode 4.2

Goto, Product -> edit scheme -> click Run yourappname.app -> Diagonostics -> Enable Zombie object.

Zigzag answered 8/11, 2011 at 12:56 Comment(0)

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Here's a video and explaination how to use Instruments and NSZombie to find and fix memory crashes on iOS: http://www.markj.net/iphone-memory-debug-nszombie/

Parsimonious answered 31/1, 2011 at 3:19 Comment(0)

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As of Xcode 3.2.5 and Snow Leopard (Mac OS X 10.6), you can run your code through the Zombies instrument: Run > Run with Performance Tool > Zombies. That allows you to see particular objects and their retain counts on a timeline.

Celindaceline answered 8/12, 2010 at 23:40 Comment(4)

I can see zombies option but it is grayed out. Do you know how it is enabled? – Blab 15/7, 2011 at 7:29

@RahulVyas, I've never seen that before, but do you have garbage collection turned on? I could see Zombies not making sense in that context – Celindaceline 18/7, 2011 at 11:43

I have turned on garbage collection in the settings it shows supported [-fobjc-gc] but still that option is disabled. Infact only last 5 options are enabled in the instruments category. Any other idea? Or am I doing something wrong? – Blab 18/7, 2011 at 12:1

@RahulVyas: Sorry, to be clearer, I thought turning garbage collection off would possibly enable Zombies, since I don't think it's possible to have a zombie with garbage collection. If that doesn't solve it, I would recommend reading the Instruments documentation (they have good write-ups on each instrument) and if you still haven't gotten it, post a question here to get wider attention (and ultimately an answer). – Celindaceline 18/7, 2011 at 16:21

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In Xcode 4.5.2 goto Product -> Edit Scheme -> and Under the Diagnostics tab check the check box in between Objective C and Enable Zombie Objects and Click on OK

Teriteria answered 7/12, 2012 at 14:37 Comment(0)

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To enable Zombie logging double-click the executable in the executables group of your Xcode project. At this point click the Arguments tab and in the Variables to be set in the environment: section, make a variable called NSZombieEnabled and set its value to YES.

Situation answered 30/4, 2011 at 10:12 Comment(0)

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In XCode 4.0: To detect NSZombie in Instruments, select the Simulator as your target (can't detect NSZomboe on device). Run Instruments (CMD+I) and select "Zombies" trace template. Enjoy.

Non answered 6/10, 2011 at 12:22 Comment(0)

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In the preferences of your executable add the environment variable NSZombieEnabled and set the value to YES.

Cecrops answered 30/4, 2011 at 10:11 Comment(0)

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in ur XCODE (4.3) next the play button :) (run)

select : edit scheme

the scheme management window will open

click on the Arguments tab

you should see : 1- Arguments passed on launch 2- environment variables

inside the the (2- environment variables) place Name: NSZombieEnabled
Value: YES

And its done....

Simper answered 17/5, 2012 at 9:41 Comment(0)

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NSZombieEnabled is used for Debugging BAD_ACCESS,

enable the NSZombiesEnabled environment variable from Xcode’s schemes sheet.

Click on Product⇒Edit Scheme to open the sheet and set the Enable Zombie Objects check box

this video will help you to see what i'm trying to say.

Meltage answered 22/10, 2013 at 8:21 Comment(1)

@kleopatra Thanks updated my answers with the appropriate setting – Meltage 22/10, 2013 at 8:45

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