Question

Subviews added to a view are automatically retained by the view. Suppose you want to have a separate pointer to the same subview so you don’t need to constantly retrieve it via its tag.

What type of @property is necessary for such a case? I assume that setting the property to retain is not a good idea since the main view is already retaining it? Should it be assign?

Or, is using @property entirely unnecessary here unless you plan to re-assign it later or refer to it with dot notation?

Answer 1

You can use either retain or assign.

Of course, if you use retain, you have to set the property to nil or release its object in viewDidUnload and dealloc.

The reason some people prefer retain is because it means the property is still valid in viewDidUnload. So if you have other cleanup to do, and that cleanup requires the view to still exist, you can do it in viewDidUnload.

If you use assign, you don’t have to set the property to nil in viewDidUnload and dealloc (though it would be good practice). However, by the time you receive viewDidUnload, the view has already been released, so you can’t use it at that point for other cleanup. Instead you have to override didReceiveMemoryWarning to do the cleanup before calling [super didReceiveMemoryWarning].

In iOS 5.0, you can do the cleanup in viewWillUnload instead of overriding didReceiveMemoryWarning.