How to maintain presenting view controller's orientation when dismissing modal view controller?

Question

I have this app I am working on and I need ALL my view controllers but one to be in portrait. The single one view controller that is special I need it to be able to rotate t

Answer 1

Awesome question and awesome answer provided by @ZaEeM ZaFaR! Combining his answer with this led me to a great and more generic solution.

The drawback of the first answer is that you have to manage the variable isPresented in every view controller that allows rotations. Furthermore, you have to expand the check and cast in supportedInterfaceOrientationsForWindow for every vc that allows rotation.

The drawback of the second answer is that it doesn't work; it also rotates the presenting vc when dismissing the presented vc.

This solution allows rotation in all vc where you put canRotate(){} and doesn't rotate the presenting vc.

Swift 3:
In AppDelegate.swift:

func application(_ application: UIApplication, supportedInterfaceOrientationsFor window: UIWindow?) -> UIInterfaceOrientationMask {
    if let rootViewController = self.topViewControllerWithRootViewController(rootViewController: window?.rootViewController) {
        if (rootViewController.responds(to: Selector(("canRotate")))) {
            // Unlock landscape view orientations for this view controller if it is not currently being dismissed
            if !rootViewController.isBeingDismissed{
                return .allButUpsideDown
            }
        }
    }

    // Only allow portrait (standard behaviour)
    return .portrait
}

private func topViewControllerWithRootViewController(rootViewController: UIViewController!) -> UIViewController? {
    if (rootViewController == nil) {
        return nil
    }
    if (rootViewController.isKind(of: UITabBarController.self)) {
        return topViewControllerWithRootViewController(rootViewController: (rootViewController as! UITabBarController).selectedViewController)
    } else if (rootViewController.isKind(of: UINavigationController.self)) {
        return topViewControllerWithRootViewController(rootViewController: (rootViewController as! UINavigationController).visibleViewController)
    } else if (rootViewController.presentedViewController != nil) {
        return topViewControllerWithRootViewController(rootViewController: rootViewController.presentedViewController)
    }
    return rootViewController
}

In each view controller where rotation should be allowed:

func canRotate(){}