Swift: Can't use navigationController.pushViewController inside a function

Question

I am transitioning between views programatically using the code below and it gets repeated quite a lot so I wanted to create a global function but I can't seem to be able to get the hang of it.

The code works when called inside a ViewController class, so I suppose the problem is that my function doesn't know which VC do I want to call navigationController.pushViewController on, but I don't know how to reference the VC either as an argument passed to the function, or better yet with something like .self to take the current VC class the function is called in.

let storyboard = UIStoryboard(name: "Main", bundle: nil)
let vc = storyboard.instantiateViewController(withIdentifier: "ExamplesControllerVC")
self.navigationController?.pushViewController(vc, animated: true)

The error I get if I try to run that as a function in a separate file is:

Use of unresolved identifier 'navigationController'; did you mean 'UINavigationController'?

So the function I'd like to create and call is something like:

showVC("ExamplesControllerVC")

Any ideas?

Answer 1

Do you want to do something like this?:

extension UIViewController {
    func presentView(withIdentifier: String) {
        if let newVC = self.storyboard?.instantiateViewController(withIdentifier: withIdentifier) {
        self.present(newVC, animated: true, completion: nil)
        }
    }
}

You can call it this way:

self.presentView(withIdentifier: "yourIdentifier")