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performSegueWithIdentifier("showInfo", sender: self);

si es push para el back:
self.navigationController?.popViewControllerAnimated(true);

let info = self.storyboard?.instantiateViewControllerWithIdentifier("InfoViewController") as? InfoViewController
let navController = UINavigationController(rootViewController: info!);
self.presentViewController(navController, animated: true, completion: nil);

para el back:
self.dismissViewControllerAnimated(true)