How to redisplay parse login from child view controller in swift

Question

I have a view controller which is triggered from a UITabBarController (which is the root of my app) if a parse session doesn't exist.

override func viewDidAppear(animated: Bool) {
    super.viewDidAppear(animated)
    self.initialiseLogin()
}

func initialiseLogin()
{
    if (PFUser.currentUser() == nil) {
        let storyboard: UIStoryboard = UIStoryboard(name: "Main", bundle: nil)
        let vc: UIViewController = storyboard.instantiateViewControllerWithIdentifier("LoginView") as! UIViewController
        self.presentViewController(vc, animated: false, completion: nil)
    }
}

Which works great. However the problem i'm having is how do i trigger this code when a logout is called from a child view controller in the tab bar controller

@IBAction func logoutAction(sender: AnyObject)
{
    PFUser.logOut()
    // ... what should i call here...
}

Answer 1

Protocols and delegates might be what you're looking for: The Swift Programming Language - Protocols

Essentially, you can declare your UIViewController s to conform to a protocol. Then set the delegates in your root view controller (or wherever you do your initialisation)

Then, you can do something like this:

@IBAction func logoutAction(sender: AnyObject)
{
    PFUser.logOut()
    delegate?.loggedOut()
}