How do you share data between view controllers and other objects in Swift?

Question

Say I have multiple view controllers in my Swift app and I want to be able to pass data between them. If I\'m several levels down in a view controller stack, how do I pass d

Answer 1

SWIFT 3:

If you have a storyboard with identified segues use:

func prepare(for segue: UIStoryboardSegue, sender: Any?)

Although if you do everything programmatically including navigation between different UIViewControllers then use the method:

func navigationController(_ navigationController: UINavigationController, willShow viewController: UIViewController, animated: Bool)

Note: to use the second way you need to make your UINavigationController, you are pushing UIViewControllers on, a delegate and it needs to conform to the protocol UINavigationControllerDelegate:

   class MyNavigationController: UINavigationController, UINavigationControllerDelegate {

    override func viewDidLoad() {
        self.delegate = self
    }

    func navigationController(_ navigationController: UINavigationController, willShow viewController: UIViewController, animated: Bool) {

     // do what ever you need before going to the next UIViewController or back
     //this method will be always called when you are pushing or popping the ViewController

    }
}