ARC, Nib files, and releasing top-level objects

Question

I have a custom controller object that loads a Nib file like so:

- (id)init {
    self = [super init];
    if (self) {
        [NSBundle loadNibNamed:@"AccountSetup" owner:self];
    }
    return self;
}

The Nib file contains a single NSTabView item. I noticed that when my custom controller object is released the tab view is not released along with it.

My custom controller object extends NSViewController and from what I read in the docs(1), top level objects in a Nib should be released automatically if the file's owner extends NSViewController:

If the File’s Owner is not an instance of NSWindowController or NSViewController, then you need to decrement the reference count of the top level objects yourself.

If I release the tab view in dealloc of the custom controller it goes away correctly, but I'm wondering if I'm missing something or if the docs are just not very precise in this particular case.

1) https://developer.apple.com/library/mac/#documentation/Cocoa/Conceptual/LoadingResources/CocoaNibs/CocoaNibs.html#//apple_ref/doc/uid/10000051i-CH4-SW18

Rob Keniger Rob Keniger · Accepted Answer · 2012-02-23T12:30:34

If your controller is a subclass of NSViewController, then you are using it incorrectly and bypassing its nib loading mechanism. You should be doing this:

- (id)init 
{
    self = [super initWithNibName:@"AccountSetup" bundle:nil];
    if (self) 
    {
        //perform any initializations
    }
    return self;
}

By bypassing the initWithNibName:bundle: method and using the NSBundle method directly, you are preventing NSViewController from managing the top-level objects in the nib.

ARC, Nib files, and releasing top-level objects

1 Answers