How to get the previous viewcontroller that pushed my current view

In Swift 3,

if let navController = self.navigationController, navController.viewControllers.count >= 2 {
     let viewController = navController.viewControllers[navController.viewControllers.count - 2]
}

You can get the previous viewController like following code,

NSLog(@"%@",[self.navigationController.viewControllers objectAtIndex:self.navigationController.viewControllers.count-2]);

This will displays the previous viewController name...

In Swift:

let n: Int! = self.navigationController?.viewControllers?.count
let myUIViewController = self.navigationController?.viewControllers[n-2] as! UIViewController