CODEWITHSUNDEEP
cocoa
Circle
Circle

Reputation: 165

Cocoa NSOutlineView bug - [NSCFTimer copyWithZone:]: unrecognized selector sent to instance

I'm using an NSOutlineView with the function 

- (BOOL)outlineView:(NSOutlineView *)outlineView
  isGroupItem:(id)item

defined so it gives the group row GUI look. When I add a root item, it works fine. When I add an item to root's child array and expand it, it works fine. If I contract the item though, the following error is logged:

[NSCFTimer copyWithZone:]: unrecognized selector sent to instance

I also get an EXC_BAD_ACCESS error if the app window is deactivated by switching to another app. I used the debugger to try to find where I might have made an error in one of my functions, but the stack trace only shows functions I did not create (RunCurrentEventLoopInMode, CFRunLoopRunSpecific, handleWindowNeedsDisplay, etc.) Does anyone have any idea where my error(s) might be?

Upvotes: 0

Views: 1856

Answers (1)

Peter Hosey
Peter Hosey

Reputation: 96373

Sounds like an object is dying prematurely. You get the “unrecognized selector sent to instance” exception when a new object is allocated later with the same pointer and then something tries to send the old object a message (in the example shown, the reincarnation is an NSTimer and the message something tried to send the previous object was copyWithZone:). You get an EXC_BAD_ACCESS crash when the object is simply garbage memory.

Debug this by running your app under Instruments with the Zombies instrument enabled. The object will, instead of dying, become a zombie object. When something tries to send a zombie a message, the zombie will moan (figuratively speaking), which will show up in Instruments's timeline as a flag. You can click a button in that flag to view the history of the object, including all of its retentions and releases.

Upvotes: 4

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