You might have noticed that when you insert an IBOutlet directly from Interface Builder you can select whether to have it as a weak or strong property. After a little search in the Apple developer’s library I have found when you should use one or the other:
Outlets should generally be weak, except for those from File’s Owner to top-level objects in a nib file (or, in iOS, a storyboard scene) which should be strong. Outlets that you create should therefore typically be weak, because:
Outlets that you create to subviews of a view controller’s view or a window controller’s window, for example, are arbitrary references between objects that do not imply ownership.
The strong outlets are frequently specified by framework classes (for example, UIViewController’s view outlet, or NSWindowController’s window outlet).
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