iOS 13: @objc VC.navigationController(_:willShow:animated:) : threading violation: expected the main thread

Question

I got the crash on Crashlytics of Fabric only for iOS 13 users when the NavigationBar of the particular ViewController is being hidden.

I tried by hiding the NavigationBar for particular ViewController by using NavigationController's delegate method

func navigationController(_ navigationController: UINavigationController, willShow viewController: UIViewController, animated: Bool) {
    let hide = (viewController is MyVC)
    navigationController.setNavigationBarHidden(hide, animated: animated)
}

But it also generating the crash on crashlytics called

Fatal Exception: NSInternalInconsistencyException

threading violation: expected the main thread

score 0 · Answer 1 · answered Oct 22 '19 at 07:35

0

Hide it on main thread

Dispatch.main.async {
    navigationController.setNavigationBarHidden(hide, animated: animated)
}

answered Oct 22 '19 at 07:35

Lu_

2,577
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Let me know if this helped – Lu_ Oct 22 '19 at 08:42
If I try to add it in main thread, then it will be hidden with a blink – Nikunj Oct 22 '19 at 08:42
then hide it without animation – Lu_ Oct 22 '19 at 08:43
and why you are not setting it in MyVC? – Lu_ Oct 22 '19 at 08:51
I used to add it in MyVC, but similar crash generated – Nikunj Oct 22 '19 at 08:52
So One of my friend suggested me to do this solution https://stackoverflow.com/questions/58335061/ios-13-threading-violation-expected-the-main-thread – Nikunj Oct 22 '19 at 08:53

score 0 · Answer 2 · answered Oct 22 '19 at 07:40

0

Do you call navigationController.setNavigationBarHidden from a background Thread?

Try:

DispatchQueue.main.async { [weak self] in
     self?.navigationController?.setNavigationBarHidden(hide, animated: animated)
}

answered Oct 22 '19 at 07:40

extrum

11
2

I don't call navigationController.setNavigationBarHidden from a background Thread. – Nikunj Oct 22 '19 at 08:43
so you say that `threading violation: expected the main thread` this error is lying? – Lu_ Oct 22 '19 at 08:44
But I just want to find why is this happening? – Nikunj Oct 22 '19 at 08:50

score 0 · Accepted Answer · answered Nov 19 '19 at 07:39

0

I got a solution for the above issue,

I used Xcode 10.2.1 to upload the build of the app, and I didn't get any crashes now.

answered Nov 19 '19 at 07:39

Nikunj

630
1
6
20

Hi Nikunj, can you pls share your answer – mouni Jan 21 '20 at 10:26

iOS 13: @objc VC.navigationController(_:willShow:animated:) : threading violation: expected the main thread

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