CODEWITHSUNDEEP
iosswiftuinavigationcontrollernavbaruinavigationitem
Astu biggi
Astu biggi

Reputation: 121

Swift - Shrink Navigation Bar on scroll

I'm really stuck here. I would like to shrink the Navigation Bar when I scroll down a UITableView and enlarge it again when scrolling up. I managed to alter the size of the Navigation Bar, but the title image is not shrinking with the Navigation Bar.

I want to do it exactly like Safari, and the problem is that the height of my TitleView is shrinking but the width never changes.

Here's the code I've used to get the height of the scrollbar to change.

func scrollViewDidScroll(scrollView: UIScrollView) {
    var navbar = navigationController?.navigationBar
    var dir:CGPoint = tableview.panGestureRecognizer.translationInView(self.tableview)
    var scrollViewHeight = tableview.frame.size.height
    var scrollContentSizeHeight = tableview.contentSize.height
    var scrollOffset = tableview.contentOffset.y

    if (dir.y > 0 && self.formernavstate == "small") {
        self.formernavstate = "big"

        UIView.animateWithDuration(0.5, delay:0.0, options: UIViewAnimationOptions.AllowAnimatedContent, animations: { () -> Void in

        println("")
        navbar?.frame.origin.y = 20
        self.navigationItem.titleView?.transform = CGAffineTransformMakeScale(0.52, 0.6)
        }, completion: nil)
    }

    if (dir.y < 0 && self.formernavstate == "big") {
        self.formernavstate = "small"   
        navbar?.frame.origin.y = 0
        navigationItem.titleView?.transform = CGAffineTransformMakeScale(0.0001, 0.2)
    }
}

Upvotes: 7

Views: 5801

Answers (1)

danywarner
danywarner

Reputation: 958

I implemented a Swift 3 version with a custom "header" and resizing it's height constraint based on @chauhan's answer:

extension ViewController: UIScrollViewDelegate {

    func scrollViewDidScroll(_ scrollView: UIScrollView) {
        if scrollViewOffset < scrollView.contentOffset.y {
            shrinkHeader(shrink: true)
        } else if scrollViewOffset > scrollView.contentOffset.y {
            shrinkHeader(shrink: false)
        }
    }

    func shrinkHeader(shrink: Bool) {
        if shrink {
            if self.headerContainerHeightConstraint.constant > CGFloat(minHeaderHeight) {
                UIView.animate(withDuration: 0.1, animations: {
                    self.headerContainerHeightConstraint.constant = self.headerContainerHeightConstraint.constant - 2
                    self.view.layoutIfNeeded()
                })
            }
        } else {
            if self.headerContainerHeightConstraint.constant < CGFloat(maxHeaderHeight) {
                UIView.animate(withDuration: 0.1, animations: {
                    self.headerContainerHeightConstraint.constant = self.headerContainerHeightConstraint.constant + 6
                    self.view.layoutIfNeeded()
                })
            }
        }
    }
}

Upvotes: 2

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