UINavigationController: show embedded view controllers with different orientations after each transition?

Question

This is a common question on StackOverflow, but none of the other solutions worked. Many were also written several years ago.

Here are some of the posts considered:<

Answer 1

Step 1

Subclass UINavigationController.

class LandscapeNavigationController: UINavigationController {
    public var vertical: Bool = true

    override var shouldAutorotate: Bool {
        get { return true }}

    override var supportedInterfaceOrientations: UIInterfaceOrientationMask {
        get { return (vertical) ? .portrait : .landscapeLeft }}

    override var preferredInterfaceOrientationForPresentation: UIInterfaceOrientation {
        get { return (vertical) ? .portrait : .landscapeLeft }}
}

Step 2

Use different UINavigationController for different orientations. Yes, pushing a new UINavigationController atop a previous UINavigationController will essentially be modal, but the transition looks nice.

For added convenience, use User Defined Runtime Attributes to control the orientation of the LandscapeNavigationController.

Step 3

Add a pop method to handle Back buttons on the now modal UIViewController.

@IBAction func doBack(_ sender: UIBarButtonItem) {
    if let navigationController = navigationController {
        navigationController.dismiss(animated: true, completion: {
        })
    }
}

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In Action

Notice how the Top and Bottom labels on view C are properly laid out.

↻ replay animation

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► Find this solution on GitHub and additional details on Swift Recipes.