Re: Setting NSObjectController's to file's owner

FROM : André Pang
DATE : Thu May 15 16:53:28 2008

On 15/05/2008, at 5:21 PM, André Pang wrote:

> I have a nib file containing an NSObjectController.  The 
> NSObjectController's content is set to the File's Owner proxy 
> object, and this creates a retain cycle.  (The file's owner never 
> gets deallocated because the object controller retains it, and the 
> object controller never gets deallocated because the file's owner 
> retains it as an IBOutlet.)


Hmm, I just created a small test application to try to reproduce this 
problem and couldn't get the retain cycle to happen.  It's a dead-
simple document-based Cocoa application with a single 
NSObjectController in the nib file, with a single text field binding 
that was bound through the object controller to an ivar in the file's 
owner.

However, now the weird thing is that I call -[objectController 
release] in the file's owner -dealloc (which I guess should be the 
correct behaviour, since the object controller is declared as an 
IBOutlet and is a top-level nib file object), I get into an infinite 
"release cycle" loop.  Test program here, for those willing to lend a 
hand:

  http://algorithm.com.au/tmp/NSObjectControllerRetainCycleTest.zip

Am I completely misunderstanding memory management of bindings/nib 
files objects?

One more note: in the application where I was having this retain cycle 
problem, I deleted the content outlet from the object controller in 
the .nib file, and instead set it programmatically via -
setContent:self in the document's -awakeFromNib, balanced by a -
setContent:nil in the document's -close method.  That fixed it, which 
strongly implied that there was a retain cycle with the object 
controller and the file's owner object (the NSDocument subclass).  I'm 
very puzzled.

Cheers,
Andre.


--
% Andre Pang : trust.in.love.to.save  <http://www.algorithm.com.au/>