Delayed presentation of UISplitViewController's content breaks on iPhone with the iOS 13 beta sdk

[nataliq]

Expected Behavior

Running the Messages example app on iPhone running iOS 13 should show the list of messages.

Current Behavior

An empty grey screen is shown.

Steps to Reproduce

1. Build and run the Messages example app with Xcode 11 on an iPhone simulator.

Context

• Operating Version: iOS 13 beta 1
• Swift version: 5.1

In the main present method of UIViewController we delay the presentation if the view controller is not loaded yet. It seems like setting the viewControllers of a UISplitViewController or a UINavigationController after it was presented in automatic mode on iPhone (showing only one of the screens), doesn't add the view controllers to the screen even though they are assigned to the property. This can be reproduced by replacing this line of code of the example app:

bag += split.present(viewController, options: [ .defaults, .showInMaster ])

with

let nc = customNavigationController([ .defaults, .showInMaster ])
nc.viewControllers = [viewController]

DispatchQueue.main.asyncAfter(deadline: .now() + .seconds(2)) {
    split.viewControllers = [nc]
}

Removing the asyncAfter call results in a correct behaviour.

Failure Logs

No logs.

[nataliq]

Dirty fix for the time being:

Add self is UISplitViewController || to the guard statement in UIViewController+Presentation.

[niil-ohlin]

Just to make sure that I understood it correctly.

// 1
bag += split.present(viewController, options: [ .defaults, .showInMaster ])

and

// 2
let nc = customNavigationController([ .defaults, .showInMaster ])
nc.viewControllers = [viewController]

DispatchQueue.main.asyncAfter(deadline: .now() + .seconds(2)) {
    split.viewControllers = [nc]
}

does not work as expected. But

// 3
let nc = customNavigationController([ .defaults, .showInMaster ])
nc.viewControllers = [viewController]

split.viewControllers = [nc]

has the correct expected behavior?

[nataliq]

Yes, exactly. See this: https://gist.github.com/nataliq/deef2efbd9ddab5e2b3bbf53dff9c0c0
I wanna file a radar but every time I go to the new feedback assistant, it's not working.

[nataliq]

I reported the issue through feedback assistant. Doesn't seem to be addressed in the latest betas too.

[nataliq]

Temporary fix implemented in 1.7.0 (#43)

[CJEkman]

Since it was discovered that this also affects UINavigationController, the dirty fix has been expanded to:

shouldPresentImmediately = root is UISplitViewController || vc is UISplitViewController || (root as? UINavigationController)?.viewControllers.isEmpty == true