How to hide navigation bar when I scroll down?

Question

I want the top section to hide when I scroll down and the navigation controller at the bottom (which isn't on the screenshot) to hide when I scroll down and reappear when scrolling up. The top part is an image with two buttons.

Answer 1

you could use the scrollView delegates for this. For example

func scrollViewDidScroll(_ scrollView: UIScrollView) {
    if scrollView.panGestureRecognizer.translation(in: scrollView.superview).y > 0 {
        //scrolling downwards
        if scrollView.contentOffset.y < 0 {
            //this means we are at top of the scrollView
            changeSectionHeight(with scrollView.contentOffset.y, hide:false)
        }
    }
    else {
        //we are scrolling upward
       changeSectionHeight(with scrollView.contentOffset.y, hide:true)
    }
}

This is how you will know when the user is scrolling down or up. Now based on that we can hide or show the top section (by changing the height constraint).

//make IBoutlet for the top section height constraint
@IBOutlet weak var topSectionHeightConstraint: NSLayoutConstraint!

func changeSectionHeight(with offset:CGFloat, hide:Bool) {

    let requiredHeight: CGFloat = hide ? 0.0 : 160.0  //let say when you want to hide the height is 0.0 and when you want to show it its 160.0

    //If you want animation when showing and hiding use animate if not then simply change the constant for the constraint
    if hide {
        if (holderViewHeightConstraint.constant - offset) > requiredHeight {
            UIView.animate(withDuration: 0.3, animations: {
                self. topSectionHeightConstraint.constant -= offset
            })
        }
        else {
            UIView.animate(withDuration: 0.3, animations: {
                self. topSectionHeightConstraint.constant = requiredHeight
            })
        }
    }
    else {
        if (holderViewHeightConstraint.constant - offset) < requiredHeight {
            UIView.animate(withDuration: 0.3, animations: {
                self. topSectionHeightConstraint.constant -= offset
            })
        }
        else {
            UIView.animate(withDuration: 0.3, animations: {
                self. topSectionHeightConstraint.constant = requiredHeight
            })
        }
    }
}