How to hide a navigation bar from first ViewController in Swift?

If you know that all other views should have the bar visible, you could use viewWillDisappear to set it to visible again.

In Swift:

override func viewWillAppear(_ animated: Bool) {
    super.viewWillAppear(animated)
    navigationController?.setNavigationBarHidden(true, animated: animated)
}

override func viewWillDisappear(_ animated: Bool) {
    super.viewWillDisappear(animated)
    navigationController?.setNavigationBarHidden(false, animated: animated)
}