I suspect that to be the case when I received this code for study.
Scenario: MyWindowController:NSWindowController ----->
MyViewController:NSViewController (a delegate)
Inside 'MyViewController':
- (id)initWithSerial:(NSString *)_serial email:(NSString *)_email
delegate:(NSObject <MyControllerProtocol>*)_delegate {
self = [super init];
serial = [_serial retain];
email = [_email retain];
//!!!: Delegating objects do not (and should not) retain their
delegates.
// However, clients of delegating objects (applications, usually) are
responsible for ensuring that their delegates are around to receive delegation
messages.
// Is 'MyController' a client of a delegating object?
delegate = [_delegate retain]; // ...should this be 'retain' or
'assign'?
return self;
}
On Jan 12, 2011, at 12:45 PM, Corbin Dunn wrote:
> Clients of delegating objects are the things that hold onto the delegating
> objects. So, for example, if you have a bunch of NSWindowController instances
> those objects are usually delegates for NSWindows. Now, the
> NSWindowControllers need someone to hold onto them. Typically your global
> NSApplication object (or something else). That object is the client of the
> NSWindowController, and needs to retain the NSWindowControllers.
>
> All delegates (in general) should be "assign" to avoid cycles. In your
> particular case, your window controller will probably need to keep track of
> all of its NSViewController instances via a retain (maybe an NSArray).
> However, even if your NSWindowController is the delegate of the
> NSViewController, it should not be retained via the delegate (by convention).
>
> corbin
If I understand you right, NSWindowController is a client (instantiated within)
the NSApplication and hence, should be retained.
Yet, NSWindowConroller is a delegate of NSWindow, so it should be assigned to
(vs retained by) NSWindow.
NSApplication ---> [NSWindowController retain] <----- delegate
[NSWindowController assign] ---- NSWindow.
This setup has a broken cycle, with the NSWindowController strongly linked to
NSApplication, yet weakly linked (as a delegate) to its host.
In my case (above) there's no delegate client, merely an object with its
delegate and hence, should be weakly linked via assign.
Ric.
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