How to have a better transition between controllers for the navigation bar?

Question

When I'm in the 2nd view controller and I press the back button, the navigation bar disappears brutally. I would like it to slide away from the screen with the view controller. And when I press a button to go to the 2nd view controller, the navigation bar appears before the 2nd view controller is on screen.

• Is there a way to have a smoother transition of the navigation bar ?
• Can you have a custom transition for the navigation bar ?

var previousStatusBarHiddenState: Bool = false

override func viewWillAppear(animated: Bool) {
    super.viewWillAppear(animated)

      // store navigationBar hidden state
      if let navigationBar = navigationController?.navigationBar {
      previousStatusBarHiddenState = navigationBar.hidden
      navigationBar.hidden = true
     }

override func viewWillDisappear(animated: Bool) {
    super.viewWillDisappear(animated)

     // restore navigationBar hidden state
     if let navigationBar = navigationController?.navigationBar {
     navigationBar.hidden = previousStatusBarHiddenState
    }

Answer 1

I found the solution :

I used navigationController.setNavigationBarHidden(true, animated: animated)

override func viewWillAppear(animated: Bool) {
    super.viewWillAppear(animated) 

       if let navigationController = navigationController {
       previousStatusBarHiddenState = navigationController.navigationBar.hidden
       navigationController.setNavigationBarHidden(true, animated: animated)
  }
}
override func viewWillDisappear(animated: Bool) {
    super.viewWillDisappear(animated)

       // restore status bar
       navigationController?.setNavigationBarHidden(previousStatusBarHiddenState, animated: animated)
}