elchapo | serverless URL shortener using python/flask with DynamoDb | Serverless library

The Nav controller doesn't "create its own instance", or at least that is a somewhat confused way of looking at it. It only appears that way if you are using storyboards. You can use a Navigation Controller without use of storyboards at all if you so wish, in which case you would manually instantiate a new View Controller to push onto the nav controller stack. If you use a storyboard, it will contain defined segue's which "cause" the next view controller to get pushed onto the stack. It is the segues in the storyboard that define which view controllers get created when. There is no need to create a singleton to "get to" the child view controllers pushed onto the navigation stack. Each time one is pushed onto the navigation controller's stack, by default it will be created, and when it is popped, unless you specifically maintain a strong reference to it (which would almost always be a bad idea) it will be destroyed.

If you haven't already subclassed your navigation view controller, do so, and in the subclass override the prepare(for:sender:) to be able from the navigation controller, to access an instance of the child view controller pushed onto the navigation controller's stack. If you want to access that view controller, either save a reference to it in that method, or, better, find it in the navigation controllers stack using one of the following properties of the navigation controller: