a bug about [UINavigationController setViewControllers: animated:]

Question

Created Jul ’16

Replies 4

Boosts 0

Views 3.6k

Participants 4

I find a bug about [UINavigationController setViewController: animated:]. and i get crash every time in iOS 9.0+. I don't try iOS 9.0-.

In my case, i have a rootViewController which has 2 childViewControllers: UINavigationControllerA, UINavigationControllerB

UINavigationControllerA has 1 childViewController, like this: UINavigationControllerA.viewControllers == [UIViewControllerA]

UINavigationControllerB also has 1 childViewController, like this: UINavigationControllerB.viewControllers == [UIViewControllerB]

then UINavigationControllerB push UIViewControllerC, so UINavigationControllerB.viewControllers == [UIViewControllerB, UIViewControllerC]

at last, put UIViewControllerC to UINavigationControllerA

[UINavigationControllerB setViewControllers:@[UIViewControllerB] animated:NO]

[UINavigationControllerA setViewControllers:@[UIViewControllerA, UIViewControllerC] animated:NO]

it will crash!

crash log:

Terminating app due to uncaught exception 'UIViewControllerHierarchyInconsistency', reason: 'child view controller:<UIViewControllerC: 0x7f7fd17453a0> should have parent view controller:<UINavigationController: 0x7f7fd2817400> but requested parent is:<UINavigationController: 0x7f7fd182f800>'

here is demo.https://github.com/l1002k/NaviSetViewControllersBugDemo

if i do [UIViewControllerC.view removeFromSuperview] before setViewControllers. it will OK, i guess the UIViewController.parentViewController reply on the UIViewController.view.superview.

Boost

Answer 1

just.do.it OP

Aug ’16

I suggest filing a bugreport.

AFAIK the problem is that UIViewControllerC first is a child of UINavigationControllerB.

And calling

[UINavigationControllerB setViewControllers:@[UIViewControllerB] animated:NO]

does not immediately remove UIViewControllerC because it works async somehow. (I've in mind I did stumble accross this issue a few years ago)

So, when calling

[UINavigationControllerA setViewControllers:@[UIViewControllerA, UIViewControllerC] animated:NO]

UINavigationControllerA may assume that UIViewControllerC does not have a parent, while it stil has one.

Maybe it's different when you call

UINavigationControllerB.viewControllers = @[UIViewControllerB];

Dirk

0

Answer 2

l1002k OP

Aug ’16

-setViewControllers will call -setViewControllers:animated:NO

it will carch too...

0

Answer 3

PPiersonAnchor OP

Apr ’18

I just ran into the issue, replying with my fix in case this can help anyone else out.

If you call layoutIfNeeded() on the navigation controller you removed the view controller from the crash won't happen.

[UINavigationControllerB setViewControllers:@[UIViewControllerB] animated:NO]
[UINavigationControllerB.view layoutIfNeeded]

[UINavigationControllerA setViewControllers:@[UIViewControllerA, UIViewControllerC] animated:NO]

0

Answer 4

Rahamaan Sherif OP

Mar ’19

I get the same issue with iOS 9.0. i have to use removeFromSuperview to avoid the crash before setViewControllers. it looks strange

0