Exception when going from compact to regular with the new UISplitViewController on iOS 14

What I found is that when you manipulate the view controllers during the transition from compact to regular, you need to put a short delay on that manipulation so that the runloop has a chance to complete first.

Hello, I used your sample project as my starting point for iOS 14's Sidebar, so first : thanks. :)

I have the same problem: I launch the app in compact mode (XS Max or your steps on iPad simulator), then I rotate the phone to go primary/secondary and it crashes.

HOWEVER, I just tried launching the app from the Home screen, without Xcode, and it works as it should be. I think it's more of a debugger/Xcode issue.

I am running into this issue as well, I hope that Apple has the time (even with the event tonight) to research this issue or communicate what we're doing wrong.

I fixed the crash by setting initially secondary, controller at the same time as primary and compact controllers.
So I had a custom class

Code Block 
class SplitController: UISplitViewController {
	override init(style: UISplitViewController.Style) {
        super.init(style: style)
        setupAppearance()
    }
   // ....
  private func setupAppearance() {
        delegate = self
        setViewController(sidebar, for: .primary)
        setViewController(TabBarController(rootTabs: rootTabs), for: .compact)
    }
}

and a sidebar had this implementation:

Code Block 
class SideBarController: UIViewController {
	override func viewDidLoad() {
		super.viewDidLoad()
		// ...
        splitViewController?.setViewController(mycontroller, for: .secondary)
    }
}

And whenever I was launching app with compact controller, it would crash when expanding to regular mode.
I solved it by modifying setupAppearance method to:

Code Block 
  private func setupAppearance() {
        delegate = self
        setViewController(sidebar, for: .primary)
        setViewController(homeController, for: .secondary)
		// or even, if you really don't care for some reason
		// setViewController(UIViewController(), for: .secondary)
        setViewController(TabBarController(rootTabs: rootTabs), for: .compact)
    }