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Re: didReceiveMemoryWarning Confusion
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Re: didReceiveMemoryWarning Confusion


  • Subject: Re: didReceiveMemoryWarning Confusion
  • From: David Duncan <email@hidden>
  • Date: Thu, 30 Apr 2009 09:49:27 -0700

On Apr 30, 2009, at 2:53 AM, Monty wrote:

I'm having some confusion understanding the expected behavior of UIViewController's response to didReceiveMemoryWarning messages. In Memory Management Programming Guide for Cocoa|Memory Management of Nib Objects, it states "Assuming that it does not have a superview, the view is disposed of..." And in template descendant code also comments "Assuming that it does not have a superview, the view is disposed of". Intuitively I would expect this would be differentiating on whether the view is displayed or not, and it's mentioned incidentally elsewhere that a view being displayed implies it has UIWindow as a superview. Is there any natural case that a view controller's view property would point to something other than the root of a view hierarchy, or is this just a circuitous way of talking about a view being displayed or not?

To be quite honest, you don't need to know the details of how it makes the decision to release the view, as long as you respect that decision. But the answer is along the lines of "if the view does not have a superview, release the view". There are exceptions however. The super view will not always be a UIWindow.


The second thing is I find this doesn't work as described in practice. Using the template Tab Bar Application as an example

This is a bug involving UITabBarControllers that causes some child view controllers to always have a super view and thus defeat the default behavior.
--
David Duncan
Apple DTS Animation and Printing


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References: 
 >didReceiveMemoryWarning Confusion (From: Monty <email@hidden>)

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