Move Up NavigationBar On Scrolling

When we scroll navigation bar, we want that navigation bar move up on scrolling down and when we scroll up navigation bar comes again. We use hidesBarsOnSwipe method, It will only hide the navigation bar no animation and leave a blank space in place of the navigation bar so do not use this method. To use proper animation, convert your navigation bar into frame and on scrolling set the value of y and then assign that frame to navigation bar and write the code didScroll delegate method oh UIScrollView.Example :-

var previousScrollViewYOffset : CGFloat = 0.0

func scrollViewDidScroll(_ scrollView: UIScrollView) {
    var frame = self.navigationController!.navigationBar.frame
    let size: CGFloat = frame.size.height - 21
    let framePercentageHidden: CGFloat = (20 - frame.origin.y) / (frame.size.height - 1)
    let scrollOffset: CGFloat = scrollView.contentOffset.y
    let scrollDiff: CGFloat = scrollOffset - self.previousScrollViewYOffset
    let scrollHeight: CGFloat = scrollView.frame.size.height
    let scrollContentSizeHeight: CGFloat = scrollView.contentSize.height + scrollView.contentInset.bottom
    if scrollOffset <= -scrollView.contentInset.top {
        frame.origin.y = 20
    }
    else if (scrollOffset + scrollHeight) >= scrollContentSizeHeight {
        frame.origin.y = -size 
    }
    else {
        frame.origin.y = min(20, max(-size, frame.origin.y - scrollDiff))
    }
    actionView.frame.origin.y = frame.origin.y + 43
    productCollectionView.frame.origin.y = actionView.frame.origin.y + 50
    self.navigationController!.navigationBar.frame = frame
    self.updateBarButtonItems((1 - framePercentageHidden))
    self.previousScrollViewYOffset = scrollOffset
}
    
func updateBarButtonItems(_ alpha: CGFloat) {
    self.navigationController!.navigationBar.alpha = alpha
}

var previousScrollViewYOffset : CGFloat = 0.0

func scrollViewDidScroll(_ scrollView: UIScrollView) {

var frame = self.navigationController!.navigationBar.frame

let size: CGFloat = frame.size.height - 21

let framePercentageHidden: CGFloat = (20 - frame.origin.y) / (frame.size.height - 1)

let scrollOffset: CGFloat = scrollView.contentOffset.y

let scrollDiff: CGFloat = scrollOffset - self.previousScrollViewYOffset

let scrollHeight: CGFloat = scrollView.frame.size.height

let scrollContentSizeHeight: CGFloat = scrollView.contentSize.height + scrollView.contentInset.bottom

if scrollOffset <= -scrollView.contentInset.top {

frame.origin.y = 20

}

else if (scrollOffset + scrollHeight) >= scrollContentSizeHeight {

frame.origin.y = -size

}

else {

frame.origin.y = min(20, max(-size, frame.origin.y - scrollDiff))

}

actionView.frame.origin.y = frame.origin.y + 43

productCollectionView.frame.origin.y = actionView.frame.origin.y + 50

self.navigationController!.navigationBar.frame = frame

self.updateBarButtonItems((1 - framePercentageHidden))

self.previousScrollViewYOffset = scrollOffset

}

func updateBarButtonItems(_ alpha: CGFloat) {

self.navigationController!.navigationBar.alpha = alpha

}

iOS UI

bhavuk chawla 18 December 2016

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Move Up NavigationBar On Scrolling

Move Up NavigationBar On Scrolling

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