How to create App Store Style Navigation Bar

I'm trying to recreate the App Store navigation bar animation. What I'm currently doing is adjusting the alpha of the navigation bar based on the scroll position.

The issue is that when you slide back the navigation bar does not appear in the previous view so I set the alpha back to one in viewWillDissapear (which doesn't work the best as seen in the gif).

With regards to the back button, if you change the alpha of the navigation bar the back button is also affected. Apple has a different back button (the circle with the arrow) when the navigation bar is not visible and this button disappears with an animation as the navigation bar appears and the default back button appears. I'm not sure if they're just overlaying a new one.

This question has been asked before but the accepted answer was to make the navigation bar transparent then change it's opacity as you scroll. This doesn't create the same effect as the default navigation bar isn't white but translucent and you also lose the border line at the bottom.

Swift 5

    override func viewWillDisappear(_ animated: Bool) {
        navigationController?.navigationBar.alpha = 1
    }
    

    
    func scrollViewDidScroll(_ scrollView: UIScrollView) {

        let currentVerticalOffset = scrollView.contentOffset.y
        
        var percentageVerticalOffset = CGFloat() //currentVerticalOffset / maximumVerticalOffset
        

        if currentVerticalOffset > collectionView.frame.size.height {
            percentageVerticalOffset = currentVerticalOffset / currentVerticalOffset
            self.title = "The Barn Owl"
            //self.navigationItem.setHidesBackButton(false, animated: true)
        } else {
            percentageVerticalOffset = currentVerticalOffset / collectionView.frame.size.height
            //self.navigationItem.setHidesBackButton(true, animated: true)
            self.title = ""
        }
        

//        let color = UIColor.init(red: 255/255.0, green: 255/255.0, blue: 255/255.0, alpha: percentageVerticalOffset)
//        navigationController?.navigationBar.backgroundColor = color
        
        navigationController?.navigationBar.alpha = percentageVerticalOffset 
        
    }