iOS 13: threading violation: expected the main thread

Question

The app is being crashed when trying to hide the navigation bar for a viewcontroller only for iOS 13 users.

I got the crash on Crashlytics of Fabric which titled as below,

Fatal Exception: NSInternalInconsistencyException

threading violation: expected the main thread

The app is being crashed on this line of viewWillAppear method,

    self.navigationController?.isNavigationBarHidden = true

To hide the navigation bar on the viewWillAppear method of UIViewController, I am using below code,

    override func viewWillAppear(_ animated: Bool) {
        self.navigationController?.isNavigationBarHidden = true
        super.viewWillAppear(animated)
    }

To show the navigation bar on the viewWillDisappear method of UIViewController, I am using below code,

    override func viewWillDisappear(_ animated: Bool) {
        self.navigationController?.isNavigationBarHidden = false
        super.viewWillDisappear(animated)
    }

Are you doing this procedure in a thread different from the Main one? — Mattia Righetti, Oct 11 '19 at 06:43
I think this way it the safe way to help you hide navigation https://stackoverflow.com/a/6418606/2454521 — Quang Dam, Oct 11 '19 at 06:59
@MattiaRighetti, I am not doing this procedure in any thread. — Nikunj, Oct 11 '19 at 07:32
@QuangDam Thanks for the solution, but Will this solution resolve the crash? — Nikunj, Oct 11 '19 at 07:33
@Nikunj, you should scroll up the page I sent you, you will see a lot of answers about the problem. I think it can be useful — Quang Dam, Oct 11 '19 at 07:45
Are you instantiating that viewController in a background thread? `threading violation: expected the main thread` is the key to your crash. — Starsky, Oct 11 '19 at 08:19
@Starsky I am not instantiating that viewController in a background thread. — Nikunj, Oct 11 '19 at 11:46
@QuangDam again I got crashes same way after applying the solution, but it is a few as compared to the previous crash, please help if you have any solution regarding 'expected the main thread' — Nikunj, Oct 21 '19 at 04:21
https://stackoverflow.com/questions/58499124 @QuangDam please checkout this issue, which I have got after applying the solution — Nikunj, Oct 23 '19 at 09:40

score 13 · Answer 1 · answered Dec 11 '19 at 14:48

13

do following action

  DispatchQueue.main.async {
    self.navigationController?.isNavigationBarHidden = false
  }

answered Dec 11 '19 at 14:48

Saeed

412
5
16

nice excelent my friend – Bruno Sosa Fast Tag Dec 16 '19 at 20:39
@karim for work with UI always have to do actions into the main thread, and for example: ```java self.navigationController?.isNavigationBarHidden = false ``` is an action that related to the view. – Saeed Jan 25 '20 at 06:47

iOS 13: threading violation: expected the main thread

1 Answers1

Linked