更改根视图控制器并关闭所有视图控制器

Question

I have an application in which if I already have a user's facebookUID saved, I present them with the MainViewController and set it as the rootViewController , and if not, I present them with the LoginViewController as the rootViewController in my AppDelegate.swift file.

Inside the MainViewController , there is a SettingsViewController screen that I present modally. Inside that settings screen I have a logout button.

My question is, how can set the rootViewController as the LoginViewController , and dismiss all the other controllers in the stack when they click the logout button?

Answer 1

You do it, in essence, exactly the same way you do it in the app delegate. But you are not in the app delegate, so you have to get there in steps:

1. From the UIApplication class you can get a reference to the shared application object.

2. From there you can get the app's delegate .

3. From there you can get the app delegate's window .

4. Now you can set the window's rootViewController .

The view controller that was the root view controller will vanish in a puff of smoke, along with all its dependent view controllers.

(This, however, is not quite how I would do it. I would have a stable root view controller whose only job is to be custom parent view controller to either the LoginViewController or the MainViewController. I'm not fond of the idea of changing root view controller's in the middle of the app. Still, it's not illegal.)

Answer 2

Try this code. You can switch to Login screen with animation. Also no risk of retaining the old viewcontrollers hierarchy

if let appWindow = UIApplication.shared.delegate?.window {

        UIView.transition(with: appWindow!,
                          duration: 0.6,
                          options: UIViewAnimationOptions.transitionFlipFromRight,
                          animations: {
                            let loginVC = LoginVC.init(nibName: "LoginVC", bundle: nil)
                            appWindow?.rootViewController = loginVC
        },
                          completion: nil)
    }