iOS Option 1: Swap the Root View Controller (Good)


Example

There are benefits to switching the root view controller, although the transition options are limited to those supported by UIViewAnimationOptions, so depending on how you wish to transition between flows might mean you have to implement a custom transition - which can be cumbersome.

You can show the Onboarding flow by simply setting the UIApplication.shared.keyWindow.rootViewController

Dismissal is handled by utilizing UIView.transition(with:) and passing the transition style as a UIViewAnimationOptions, in this case Cross Dissolve. (Flips and Curls are also supported).

You also have to set the frame of the Main view before you transition back to it, as you're instantiating it for the first time.

// MARK: - Onboarding

extension AppDelegate {

    func showOnboarding() {
        if let window = UIApplication.shared.keyWindow, let onboardingViewController = UIStoryboard(name: "Onboarding", bundle: nil).instantiateInitialViewController() as? OnboardingViewController {
            onboardingViewController.delegate = self
            window.rootViewController = onboardingViewController
        }
    }

    func hideOnboarding() {
        if let window = UIApplication.shared.keyWindow, let mainViewController = UIStoryboard(name: "Main", bundle: nil).instantiateInitialViewController() {
            mainViewController.view.frame = window.bounds
            UIView.transition(with: window, duration: 0.5, options: .transitionCrossDissolve, animations: {
                window.rootViewController = mainViewController
            }, completion: nil)
        }
    }
}