iOS 13: threading violation: expected the main thread

Question

Nikunj Gabani OP

Created Oct ’19

Replies 3

Boosts 0

Views 6.3k

Participants 2

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

- 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)
}

Please help.

Thanks

Boost

Answer 1

Claude31 OP

Oct ’19

Just put it in the mainQueue:

func navigationController(_ navigationController: UINavigationController, willShow viewController: UIViewController, animated: Bool) {
  let hide = (viewController is MyVC)
  DispatchQueue.main.async { () -> Void in
       self.navigationController.setNavigationBarHidden(hide, animated: animated)
   }
}

If still some problem, maybe you could also use didShoiw instead of willShow

0

Answer 2

Nikunj Gabani OP

Oct ’19

Thanks for the answer,

if I use a mainQueue, then it first being shown the NavigationBar for a second then it is being hidden

0

Answer 3

Claude31 OP

Oct ’19

So, you have no crash anymore ?

Could you explain (post code) where and how you call the navController that calls the function ?

But I would need to check something:

func navigationController(_ navigationController: UINavigationController, willShow viewController: UIViewController, animated: Bool) { 
  let hide = (viewController is MyVC) 
  DispatchQueue.main.async { () -> Void in 
       self.navigationController.setNavigationBarHidden(hide, animated: animated) 
   } 
}

Line 2, I understand MyVC is a VC that holds the navBar ?

If so, hide is true ?

Hence, line 4, you ask to hide the bar !

So it goes hidden.

Or am I missing somethging ?

0