Bug 5181 - Inconsistent finalization behavior when popping UIViewController
Summary: Inconsistent finalization behavior when popping UIViewController
Status: RESOLVED DUPLICATE of bug 1889
Alias: None
Product: iOS
Classification: Xamarin
Component: XI runtime ()
Version: 5.2
Hardware: Macintosh Mac OS
: --- normal
Target Milestone: Untriaged
Assignee: Bugzilla
Depends on:
Reported: 2012-05-18 16:59 UTC by Tobias Skarman
Modified: 2012-05-18 17:16 UTC (History)
2 users (show)

Is this bug a regression?: ---
Last known good build:

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Description Tobias Skarman 2012-05-18 16:59:24 UTC
A popped UIViewController's finalizer will not get called before the next PushViewController() call on the same UINavigationController.

If however PopViewControllerAnimated() is overridden in this fashion

        public override UIViewController PopViewControllerAnimated(bool animated)
            return base.PopViewControllerAnimated(animated);

a UIViewController's finalizer is called immediately after a 'pop'

First, I put it off as random GC behavior. But the behavior is consistent.

(1) overriden PopViewControllerAnimated: immediate finalization
(2) no overriden PopViewControllerAnimated: finalization after an arbitrary number of 'pop's and then one 'push'

Not sure if this is a bug. But the expected behavior in both cases would be that in (1) seeing how it seems to be possible to force it. It makes dealing with memory release that much easier and intuitive.

Please advise if I can rely on any of the behaviors
Comment 1 Rolf Bjarne Kvinge [MSFT] 2012-05-18 17:16:51 UTC
This is because managed code keeps a cache of the current view controllers, which is only updated when you push a new view controller (since no managed code is usually executed when a view controller is pushed, unless you override PopViewControllerAnimated - and then the cache is updated for pops too).

In any case this has already been filed as bug #1889.

*** This bug has been marked as a duplicate of bug 1889 ***