Comments on: Memory Management and NIBs on the iPhone

By: Aman

Aman — Fri, 19 Feb 2010 11:03:03 +0000

If you don’t release it on dealloc it will raise the memory footprint.

See more detail here with instrument ObjectAlloc graph: http://amanpages.com/iphone-app-development-core-sdk-cocoa/iphone-iboutlet-should-be-released-manually/

By: John

John — Thu, 29 Jan 2009 17:17:23 +0000

On the point about using assign on an IBOutlet property: not sure this is such a good idea. If you don’t retain your IBOutlet it’s quite possible to have bits and pieces failing to remain loaded after you load from the NIB, if they’re not immediately pushed onto a view or controller somewhere that will retain them. The expectation of a user of a class using the interface builder is that something attached to an IBOutlet will get retained.

On the point about dealloc methods. The ‘.’ accessor syntax is confusing for anyone who’s not too familiar with Objective C, and there are situations in which setX accessors with side-effects are useful such as in a utility class. Moreover, setX accessors can be overridden by subclasses, which is a good reason why calling them from dealloc probably isn’t such a good idea, since the subclass will already have dealloc’d.

By: Ben

Ben — Wed, 21 Jan 2009 21:12:40 +0000

I read the article you reference, but I’m missing the point.

a) I was suggesting that accessors were useful because if you swap from assign to retain properties or vice versa, everything still works
b) I see no immediate reason not to use accessor methods for properties in dealloc. Obviously they should not be used after calling [super dealloc] – but that should be the last thing you do anyway. Obviously you should also be aware of side-effects – but it is the side effect of the implicit release call that I specifically want here! You may argue that the order in which the accessors are called matters, or that they have other side effects that cannot be easily handled – I would argue that is a deficiency in the design and makes the code brittle in its own right – and should be fixed, rather than working around it.
c) The article you reference indicates that UIViewController itself calls an accessor method in dealloc – the specific construct you are saying is bad.
d) How do you have a declared property without having an accessor? I admit it will compile, but you will get a warning.

By: mmalc

mmalc — Wed, 21 Jan 2009 03:04:09 +0000

This is dreadfully confused, and conflates the syntactic sugar of declared properties with the presence or absence of accessor methods.
Moreover, you should *not* use accessor methods in dealloc.
For a more detailed discussion, see http://stackoverflow.com/questions/61838