Open Radar

 
Area:
UIKit

Summary:

When an empty array of view controllers is set on a UINavigationController, and shortly after an array with some view controller is set, UINavigationController won't display latest change - it will stay empty until you rotate the screen. This is reproducible always when `animated` flag is set to true on `setViewControllers([], animated: true)` method call.

Steps to Reproduce:

Create an empty UINavigationController, set empty view controller array using `setViewControllers([], animated: true)` and then call again `setViewController`, but with some view controller in array: `nav.setViewControllers([vc], animated: true)`.

This can be easily reproducible using this snippet inside `didFinishLaunchingWithOptions` method in AppDelegate:

```
let nav = UINavigationController()
window?.rootViewController = nav
/// Somwhere inside the app
nav.setViewControllers([], animated: true)

let vc = UIViewController()
vc.view.backgroundColor = .red
nav.setViewControllers([vc], animated: true)
/// If you rotate the device - the red view controller will show up

return true
```

Expected Results:

The view controller with red background should be visible.

Actual Results:

There is a black screen without the red view controller in the hierarchy.

Version/Build:

Version 10.1 (10B61)

Configuration:

Device iPhone X 12.1.4, iOS Simulator iPhone SE 12.1