Open Radar

 
Area:
UIKit

Summary:
Xcode’s project template for “Master-Detail Application” has a mis-configured storyboard that triggers a bug in either `UINavigationController` or `UISplitViewController`.

The bug causes certain callbacks on the detail view controller to not be fired on dismissal/pop-back. This bug affects both iPhone (without split-view) and iPad (with split-view).

Steps to Reproduce:
1. Create new Xcode Project.
2. Choose Master-Detail iOS Application
3. Add the following to `DetailViewController`:

```
override func viewDidDisappear(_ animated: Bool) {
    super.viewDidDisappear(animated)

    if self.isMovingFromParentViewController || self.isBeingDismissed {
        print(type(of: self), #function)
    }
}

override func willMove(toParentViewController parent: UIViewController?) {
    super.willMove(toParentViewController: parent)

    if parent == nil {
        print(type(of: self), #function)
    }
}

override func didMove(toParentViewController parent: UIViewController?) {
    super.didMove(toParentViewController: parent)

    if parent == nil {
        print(type(of: self), #function)
    }
}
```

4. Launch app
5. Create entry in `MasterViewController` by tapping '+'.
6. Tap on entry to open `DetailViewController`.
7. Tap back-button
8. Check console.
9. Realize that none of the expected logs are printed.

Workaround/Fix:

1. Open Main.storyboard.
2. Remove "showDetail"-Segue from `MasterViewController` to `DetailViewController`.
3. Add a `detailNavigationController` property to `MasterViewController`:

```
var detailNavigationController: UINavigationController? = nil
```

4. Replace:

```
detailViewController = (controllers[controllers.count-1] as! UINavigationController).topViewController as? DetailViewController
```

with:

```
detailNavigationController = controllers[controllers.count-1] as? UINavigationController
detailViewController = detailNavigationController!.topViewController as? DetailViewController
```

in `MasterViewController`.

5. Replace:

```
let controller = (segue.destination as! UINavigationController).topViewController as! DetailViewController
```

with:

```
let controller = segue.destination as! DetailViewController
```

in `MasterViewController`.

6. Add this:

```
override func tableView(_ tableView: UITableView, didSelectRowAt indexPath: IndexPath) {
    let storyboard = UIStoryboard(name: "Main", bundle: nil)
    let detailViewController = storyboard.instantiateViewController(withIdentifier: "detailViewController") as! DetailViewController

    let object = objects[indexPath.row] as! NSDate
    detailViewController.detailItem = object
    detailViewController.navigationItem.leftBarButtonItem = splitViewController?.displayModeButtonItem
    detailViewController.navigationItem.leftItemsSupplementBackButton = true

    if let split = splitViewController {
        split.showDetailViewController(detailViewController, sender: nil)
    } else {
        navigationController?.pushViewController(detailViewController, animated: true)
    }
}
```

in `MasterViewController`.

Expected Results:
Console:
```
DetailViewController … willMove(toParentViewController:)
DetailViewController … viewDidDisappear
DetailViewController … didMove(toParentViewController:)
```

Observed Results:
No such output.

Version:
10.x