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iosuinavigationitem

Two UINavigationItems?

Could anyone explain why there are two navigationItems? When I log like below:

NSLog(@"%@", self.navigationItem);
NSLog(@"%@", self.navigationController.navigationItem);

I get two different instances of UINavigationItem:

<UINavigationItem: 0x7f85b06f5a20>
<UINavigationItem: 0x7f85b06ab640>

I have only created a UINavigationController programmatically once.

Solution

  • All UIViewControllers have a property navigationItem. Therefore, because UINavigationController is a subclass of UIViewController, it also has this property.

    self.navigationItem will be the one presented when your controller is pushed. The documentation for navigationItem, it's clear about this property

    This is a unique instance of UINavigationItem created to represent the view controller when it is pushed onto a navigation controller.

    self.navigationController.navigationItem would be the item displayed if Apple allowed UINavigationControllers to be nested. However, since this isn't allowed, it's best to forget about it.