How to go back to the mainviewController with animation. I can do without animation.

My code:
func viewDidLoad() {

let Screen = storyboard?.instantiateViewController(withIdentifier: "sampleVC") as! SampleViewController

self.sampleVC = UINavigationController(rootViewController: Screen)
}

@IBAction func close(_ sender: Any) {

// slideMenuController()?.toggleLeft()

self.slideMenuController()?.changeMainViewController(sampleVC, close: true)
}

**While closing the viewcontroller by pressing the back button it has to go the SampleViewController with animation(Like modal view or push view). How can i achieve it ? Please guide.**