how to move from one view Controller to another without using a button - swift3

Question

I am using the following code snippet:
let secondViewController = self.storyboard?.instantiateViewController(withIdentifier: "secondViewController") as! secondViewController
self.navigationController.pushViewController(secondViewController, animated: true)
I want to execute this code in the viewDidLoad. I will be using something like this in a series of if statements.
I used some code I found here that utilized a label. It did not work. Can a program move from one viewController without using a button? Almost every example, youtube video uses a button. I will be using a button when it is appropriate

Answer 1

You can not push view controllers before your current view controller loads. You should call your code in your viewDidAppear.
If you plan on directing to a particular view when the app launches I suggest you moving your logic to the AppDelegate in the method: didFinishLaunching. This way you don't need to unnecessarily load views.
Example of a ViewController being pushed in the viewDidAppear:
///
/// FUNCTION - VIEW DID APPEAR
///
override func viewDidAppear(_ animated: Bool) {
// GET VIEW CONTROLLER
let secondViewController = self.storyboard?.instantiateViewController(withIdentifier: "secondViewController") as! secondViewController
// PUSH VIEW ONTOP OF CURRENT NAVIGATION CONTROLLER
self.navigationController.pushViewController(secondViewController, animated: true)
} // END - FUNCTION