hidesBarsOnSwipe 向上滚动时不再显示导航栏

Question

所以我想在向下滚动时隐藏导航栏并在向上滚动时将其恢复。隐藏它与

完美配合

self.navigationController?.hidesBarsOnSwipe = true

但我希望它在向上滚动时再次显示。我做了一个测试项目，其中视图控制器只有一个覆盖整个屏幕的 UICollectionView。然后按预期再次显示导航栏，直到我将此行添加到 viewDidLoad （将单元格添加到集合视图）：

self.collectionView.delegate = self

这就是整个视图控制器的样子

class ViewController: UIViewController,UICollectionViewDataSource, UICollectionViewDelegate {

@IBOutlet var collectionView: UICollectionView!
override func viewDidLoad() {
    super.viewDidLoad()
    self.collectionView.dataSource = self
    self.collectionView.delegate = self
    self.collectionView.registerClass(UICollectionViewCell.self, forCellWithReuseIdentifier: "Test")
    self.navigationController?.hidesBarsOnSwipe = true
}

func collectionView(collectionView: UICollectionView, numberOfItemsInSection section: Int) -> Int {
    return 3
}

func numberOfSectionsInCollectionView(collectionView: UICollectionView) -> Int {
    return 1
}

func collectionView(collectionView: UICollectionView, cellForItemAtIndexPath indexPath: NSIndexPath) -> UICollectionViewCell {
    return collectionView.dequeueReusableCellWithReuseIdentifier("Test", forIndexPath: indexPath) as UICollectionViewCell
}

func collectionView(collectionView: UICollectionView, layout collectionViewLayout: UICollectionViewLayout, sizeForItemAtIndexPath indexPath: NSIndexPath) -> CGSize {
    return CGSizeMake(300, 300)
}
}

那么，当我将单元格添加到我的集合视图时，为什么显示导航栏会停止工作？

Answer 1

要使hidesBarsOnSwipe 正常工作，您的视图控制器的view 必须只包含UITableView 实例，不能包含其他任何内容。

Answer 2

我尝试在 ViewDidLoad 函数中的 ViewController 类中将 hidesBarsOnSwipe 属性设置为 true，如下所示，但它无法处理在向上滑动时隐藏导航栏和在向下滑动时取消隐藏导航栏。

class ViewController: UIViewController {

   override func viewDidLoad() {
      super.viewDidLoad()
      self.navigationController?.hidesBarsOnSwipe = true
   }
}

将 hidesBarsOnSwipe 设置为 true 仅当我们使用 UITableViewController 或 UICollectionViewController 作为主屏幕时才会生效，如果我们将 UITableView 添加到 UIViewController，hidesBarsOnSwipe 将不起作用用于显示数据列表。

解决方案

class TestTableViewController: UITableViewController {

    override func viewDidLoad() {
       super.viewDidLoad()
       self.navigationController?.hidesBarsOnSwipe = true
    }
}

希望这个答案可能会有所帮助...！

Answer 3

我有同样的问题。当我添加隐藏状态栏和导航栏的代码时，它起作用了。

- (BOOL)prefersStatusBarHidden {
  return self.navigationController.isNavigationBarHidden;
}

Answer 4

根据之前的 cmets - 这似乎是 ios 10.3 的错误

当您使用 uicollectionview - 我提请您注意我从 APDynamicHeaderTableViewController 重新编写的一些代码 https://github.com/aaronpang/APDynamicHeaderTableViewController/issues/4

它正在使用 snapkit https://github.com/SnapKit/SnapKit

（向所有 IB + NSLayout 约束爱好者道歉。）

class APDynamicHeaderTableViewController : UIViewController {

  var largeWideSize = CGSize(width: UIScreen.main.bounds.width , height: 285 )
  let headerView = APDynamicHeaderView () // Change your header view here

  let cellLayout: UICollectionViewFlowLayout = UICollectionViewFlowLayout()
  var feedCV:UICollectionView!

  fileprivate var headerViewHeight:CGFloat = 80 // this will be updated by scrolling
  fileprivate var headerBeganCollapsed = false
  fileprivate var collapsedHeaderViewHeight : CGFloat = UIApplication.shared.statusBarFrame.height
  fileprivate var expandedHeaderViewHeight : CGFloat = 100
  fileprivate var headerExpandDelay : CGFloat = 100
  fileprivate var tableViewScrollOffsetBeginDraggingY : CGFloat = 0.0


  init(collapsedHeaderViewHeight : CGFloat, expandedHeaderViewHeight : CGFloat, headerExpandDelay :CGFloat) {
    self.collapsedHeaderViewHeight = collapsedHeaderViewHeight
    self.expandedHeaderViewHeight = expandedHeaderViewHeight
    self.headerExpandDelay = headerExpandDelay
    super.init(nibName: nil, bundle: nil)


  }


  init () {
    super.init(nibName: nil, bundle: nil)

  }

  required init(coder aDecoder: NSCoder) {
    fatalError("init(coder:) has not been implemented")
  }

  override func loadView() {
    super.loadView()
    self.view.backgroundColor = .green

    // Cell Layout Sizes
    cellLayout.scrollDirection = .vertical
    cellLayout.sectionInset = UIEdgeInsets(top: 0, left: 10, bottom: 0, right: 10)
    cellLayout.itemSize = CGSize(width: UIScreen.main.bounds.width, height: 185 + 80)


    // Header view
    self.view.addSubview(headerView)
    headerView.snp.remakeConstraints { (make) -> Void in
        make.top.left.equalToSuperview()
        make.width.equalToSuperview()
        make.height.equalTo(headerViewHeight)
    }

    // CollectionView
    feedCV = UICollectionView(frame: .zero, collectionViewLayout: cellLayout)
    self.view.addSubview(feedCV)
    self.feedCV.snp.remakeConstraints { (make) -> Void in
        make.top.equalTo(headerView.snp.bottom) // this is pegged to the header view which is going to grow in height
        make.left.equalToSuperview()
        make.width.equalToSuperview()
        make.bottom.equalToSuperview()
    }



    feedCV.backgroundColor = .red
    feedCV.showsVerticalScrollIndicator = true
    feedCV.isScrollEnabled = true
    feedCV.bounces = true
    feedCV.delegate = self
    feedCV.dataSource = self

     // YOUR COLLECTIONVIEW CELL HERE!!!!!
    feedCV.register(VideoCollectionViewCell.self, forCellWithReuseIdentifier: VideoCollectionViewCell.ID)


  }

  // Animate the header view to collapsed or expanded if it is dragged only partially
  func animateHeaderViewHeight () -> Void {
    Logger.verbose("animateHeaderViewHeight")

    var headerViewHeightDestinationConstant : CGFloat = 0.0
    if (headerViewHeight < ((expandedHeaderViewHeight - collapsedHeaderViewHeight) / 2.0 + collapsedHeaderViewHeight)) {
      headerViewHeightDestinationConstant = collapsedHeaderViewHeight
    } else {
      headerViewHeightDestinationConstant = expandedHeaderViewHeight
    }

    if (headerViewHeight != expandedHeaderViewHeight && headerViewHeight != collapsedHeaderViewHeight) {
      let animationDuration = 0.25
      UIView.animate(withDuration: animationDuration, animations: { () -> Void in
        self.headerViewHeight = headerViewHeightDestinationConstant
        let progress = (self.headerViewHeight - self.collapsedHeaderViewHeight) / (self.expandedHeaderViewHeight - self.collapsedHeaderViewHeight)
        self.headerView.expandToProgress(progress)
        self.view.layoutIfNeeded()
      })
    }
  }
}

extension APDynamicHeaderTableViewController : UICollectionViewDelegate {

}

extension APDynamicHeaderTableViewController : UIScrollViewDelegate {
  func scrollViewWillBeginDragging(_ scrollView: UIScrollView) {
    // Clamp the beginning point to 0 and the max content offset to prevent unintentional resizing when dragging during rubber banding
    tableViewScrollOffsetBeginDraggingY = min(max(scrollView.contentOffset.y, 0), scrollView.contentSize.height - scrollView.frame.size.height)

    // Keep track of whether or not the header was collapsed to determine if we can add the delay of expansion
    headerBeganCollapsed = (headerViewHeight == collapsedHeaderViewHeight)
  }

  func scrollViewDidScroll(_ scrollView: UIScrollView) {
    // Do nothing if the table view is not scrollable
    if feedCV.contentSize.height < feedCV.bounds.height {
      return
    }
    var contentOffsetY = feedCV.contentOffset.y - tableViewScrollOffsetBeginDraggingY
    // Add a delay to expanding the header only if the user began scrolling below the allotted amount of space to actually expand the header with no delay (e.g. If it takes 30 pixels to scroll up the scrollview to expand the header then don't add the delay of the user started scrolling at 10 pixels)
    if tableViewScrollOffsetBeginDraggingY > ((expandedHeaderViewHeight - collapsedHeaderViewHeight) + headerExpandDelay) && contentOffsetY < 0 && headerBeganCollapsed {
      contentOffsetY = contentOffsetY + headerExpandDelay
    }
    // Calculate how much the header height will change so we can readjust the table view's content offset so it doesn't scroll while we change the height of the header
    let changeInHeaderViewHeight = headerViewHeight - min(max(headerViewHeight - contentOffsetY, collapsedHeaderViewHeight), expandedHeaderViewHeight)
    headerViewHeight = min(max(headerViewHeight - contentOffsetY, collapsedHeaderViewHeight), expandedHeaderViewHeight)
    let progress = (headerViewHeight - collapsedHeaderViewHeight) / (expandedHeaderViewHeight - collapsedHeaderViewHeight)
//    Logger.verbose("headerViewHeight:",headerViewHeight)
    headerView.expandToProgress(progress)
    headerView.snp.updateConstraints { (make) -> Void in
        make.height.equalTo(headerViewHeight)
    }

    // When the header view height is changing, freeze the content in the table view
    if headerViewHeight != collapsedHeaderViewHeight && headerViewHeight != expandedHeaderViewHeight {
        feedCV.contentOffset = CGPoint(x: 0, y: feedCV.contentOffset.y - changeInHeaderViewHeight)
    }
  }

  // Animate the header view when the user ends dragging or flicks the scroll view 
  func scrollViewDidEndDecelerating(_ scrollView: UIScrollView) {
    animateHeaderViewHeight()
  }

  func scrollViewDidEndDragging(_ scrollView: UIScrollView, willDecelerate decelerate: Bool) {
    animateHeaderViewHeight()
  }
}

extension APDynamicHeaderTableViewController : UICollectionViewDataSource {
    func collectionView(_ collectionView: UICollectionView, numberOfItemsInSection section: Int) -> Int {
        return 100
    }

    func collectionView(_ collectionView: UICollectionView, cellForItemAt indexPath: IndexPath) -> UICollectionViewCell {
        let cell = collectionView.dequeueReusableCell(withReuseIdentifier: VideoCollectionViewCell.ID, for: indexPath) as! VideoCollectionViewCell

        return cell
    }


    func collectionView(_ collectionView: UICollectionView, didSelectItemAt indexPath: IndexPath) {

    }



     func collectionView(_ collectionView: UICollectionView, layout collectionViewLayout: UICollectionViewLayout, sizeForItemAt indexPath: IndexPath) -> CGSize {
        return largeWideSize
    }




}

Answer 5

扩展Oleg's answer...

如果您使用 Interface Builder 为视图控制器的主视图设置约束，Xcode 默认显示选项以根据顶部布局指南设置垂直约束。但是，如果您按“选项”，您将看到一组备用约束。 'Top Space to Container' 的约束就是你要找的。​​p>

Answer 6

我遇到了同样的问题，但使用的是网络视图。 问题是 web view 的 top 约束是 "Top Layout Guide.Top" ，将 top 约束改为 "Superview.Top" 后问题就解决了。

Answer 7

我向 Apple 提交了错误报告，最终改用 AMScrollingNavbar，它运行良好且易于设置。