Swift 中的 UITableViewCell 中的 UIScrollView

Question

我正在尝试将 UIScrollView() 添加到我的 table 的其中一个单元格中。我很难弄清楚用什么方法来放置滚动视图的代码。

我在我的应用程序的其他地方有一个滚动视图，这是我用来转移到我的 UITableView() 视图的代码，我猜它应该是：

var page = Int()
var pageViews: [UIImageView?] = []
var sixPlusImages = [
    UIImage(named: "Glance 5.5"),
    UIImage(named: "Currencies 5.5"),
    UIImage(named: "Swipe 5.5"),
    UIImage(named: "Format 5.5"),
    UIImage(named: "Search 5.5")
]

func tableView(tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
    return 1
}

func tableView(tableView: UITableView, cellForRowAtIndexPath indexPath: NSIndexPath) -> UITableViewCell {
    var cell:AppImagesTableViewCell = self.appTableView.dequeueReusableCellWithIdentifier("appImages", forIndexPath: indexPath) as! AppImagesTableViewCell

    return cell
}

func loadPage(page: Int) {
    let cell = appTableView.cellForRowAtIndexPath(NSIndexPath(index: 0))

    if page < 0 || page >= pageViews.count {
        return
    }

    if let pageView = pageViews[page] {
        return
    } else {
        var imageFrame = CGRect(x: (cell.scrollView.bounds.width * CGFloat(page)) + 5, y: 0, width: (cell.scrollView.bounds.width) - 10, height: 40)

        let imageView = UIImageView()
        imageView.contentMode = .ScaleAspectFit
        imageView.frame = imageFrame
        imageView.image = sixPlusImages[page]
        cell.scrollView.addSubview(imageView)
    }

    pageViews[page] = imageView
}

func purgePage(page: Int) {
    if page < 0 || page >= sixPlusImages.count {
        return
    }

    if let pageView = pageViews[page] {
        pageView.removeFromSuperview()
        pageViews[page] = nil
    }
}

func loadVisiblePages() {
    let pageWidth = cell.scrollView.frame.size.width
    page = Int(floor((cell.scrollView.contentOffset.x * 2.0 + pageWidth) / (pageWidth * 2.0)))

    pageControl.currentPage = page

    let firstPage = page - 1
    let lastPage = page + 1

    for var index = 0; index < firstPage; ++index {
        purgePage(index)
    }

    for index in firstPage...lastPage {
        loadPage(index)
    }

    for var index = lastPage+1; index < sixPlusImages.count; ++index {
        purgePage(index)
    }
}

func scrollViewDidScroll(scrollView: UIScrollView) {
    loadVisiblePages()
}

显然，它存在很多问题。我似乎无法访问单元格 class 中作为出口的 scrollView，这导致了一些问题。

谁能给我一些指导？我看不到任何 Swift 在线示例。

谢谢。

Answer 1

我注意到您正在使用 UIScrollView Tutorial: Getting Started 教程中建议的部分代码来使用 UIScrollView.

制作幻灯片

您可以在自定义 UITableViewCell 中使用 UIScrollView 没有任何问题，首先您必须在 CustomTableViewCell 中声明您的 @IBOutlet。

class CustomTableViewCell 必须实现协议 UIScrollViewDelegate 才能通知它有关 UIScrollView 的更改，您必须实现处理 UIScrollView 在里面。让我们看看下面的例子：

CustomTableViewCell to handle the UIScrollView

class CustomTableViewCell: UITableViewCell, UIScrollViewDelegate {


   @IBOutlet weak var scrollView: UIScrollView!

   var pageImages: [UIImage] = []
   var pageViews: [UIImageView?] = []


   override func awakeFromNib() {
      super.awakeFromNib()        

      // 1
      pageImages = [UIImage(named: "photo1.jpg")!,
         UIImage(named: "photo2.jpg")!,
         UIImage(named: "photo3.jpg")!]            

      let pageCount = pageImages.count       

      // 3
      for _ in 0..<pageCount {
          pageViews.append(nil)
      }

      // 4
      let pagesScrollViewSize = scrollView.frame.size
      scrollView.contentSize = CGSize(width: pagesScrollViewSize.width * CGFloat(pageImages.count),
        height: pagesScrollViewSize.height)

      // 5
      loadVisiblePages()        
  }

  func loadPage(page: Int) {
       if page < 0 || page >= pageImages.count {
          // If it's outside the range of what you have to display, then do nothing
          return
       }

       // 1
       if let pageView = pageViews[page] {
          // Do nothing. The view is already loaded.
       } else {
          // 2
          var frame = scrollView.bounds
          frame.origin.x = frame.size.width * CGFloat(page)
          frame.origin.y = 0.0

          // 3
          let newPageView = UIImageView(image: pageImages[page])
          newPageView.contentMode = .ScaleAspectFit
          newPageView.frame = frame
          scrollView.addSubview(newPageView)

          // 4
          pageViews[page] = newPageView
       }
   }

   func loadVisiblePages() {
      // First, determine which page is currently visible
      let pageWidth = scrollView.frame.size.width
      let page = Int(floor((scrollView.contentOffset.x * 2.0 + pageWidth) / (pageWidth * 2.0)))

      // Work out which pages you want to load
      let firstPage = page - 1
      let lastPage = page + 1

      // Purge anything before the first page
      for var index = 0; index < firstPage; ++index {
         purgePage(index)
      }

      // Load pages in our range
      for index in firstPage...lastPage {
         loadPage(index)
      }

      // Purge anything after the last page
      for var index = lastPage+1; index < pageImages.count; ++index {
         purgePage(index)
      }
   }

   func scrollViewDidScroll(scrollView: UIScrollView) {
      // Load the pages that are now on screen
      loadVisiblePages()
   }

   func purgePage(page: Int) {
       if page < 0 || page >= pageImages.count {
          // If it's outside the range of what you have to display, then do nothing
         return
       }

       // Remove a page from the scroll view and reset the container array
       if let pageView = pageViews[page] {
          pageView.removeFromSuperview()
          pageViews[page] = nil
       }
   }

   override func setSelected(selected: Bool, animated: Bool) {
      super.setSelected(selected, animated: animated)

      // Configure the view for the selected state
   }
}

那么在你的cellForRowAtIndexPath中你的UITableViewController或ViewController中你唯一需要的就是下面的代码：

override func tableView(tableView: UITableView, cellForRowAtIndexPath indexPath: NSIndexPath) -> UITableViewCell {

    let cell = tableView.dequeueReusableCellWithIdentifier("Cell", forIndexPath: indexPath) as! CustomTableViewCell        

    return cell
}

以上代码仅为示例，您必须考虑UIScrollView的约束，启用Paging Enabled等

希望对你有所帮助。

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