Question

我有一个可扩展的UITableView，它通过父单元格的插入/删除调用添加/删除子UITableViewCells。每个子单元格都包含一个WKWebView对象，我用它来渲染一些本地HTML字符串，并在加载字符串后根据内容高度调整单元格的大小。

如果我通过一次点击一个父单元格来缓慢扩展tableview，一切正常。但是，如果我尝试一次加载多个子单元格，或者快速加载同一个单元格（例如，通过快速连续点击几次父单元格），webview将无法加载内容并显示为空白。

我有一种感觉，因为我想在之前的加载完成之前再次调用WKWebView的didFinishNavigation。有没有办法阻止它在加载之前重新调用它（即在CellForRowAt方法中同步加载单元格？另外的建议也欢迎。下面的相关代码。

另外值得注意的是 - 我通过委托将SectionContentTableViewCell（孩子）的内容高度发送到视图控制器，然后我可以调用heightForRowAt。高度存储在结构中以加速后续重新加载。

class SectionContentTableViewCell: UITableViewCell, WKNavigationDelegate {

var webView: WKWebView?
var htmlString = ""
var contentSection: Int = 0
weak var contentDelegate: ContentCellDelegate? = nil

override func layoutSubviews() {
    super.layoutSubviews()

    webView?.navigationDelegate = self
    webView?.autoresizingMask = .flexibleWidth
}

func configureWebView() {
    webView?.loadHTMLString(htmlString, baseURL: URL(fileURLWithPath: Bundle.main.path(forResource: "cases", ofType: "css")!))
}

func webView(_ webView: WKWebView, didFinish navigation: WKNavigation!) {
    self.perform(#selector(webViewLoadCompleted), with: nil, afterDelay: 0.1)
}


func webViewLoadCompleted() {
    let cellHeight: CGFloat = (webView?.scrollView.contentSize.height)!
    print("cellHeight \(String(describing: cellHeight))")
    webView?.frame.size.height = cellHeight
    contentDelegate?.sendContentCellHeightData(cellHeight: cellHeight, section: contentSection)
}
}

func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
        switch visibleQuestionRowsArray[indexPath.row] {
        //Value 0 = section cell
        case 0:
            let sectionCell = tableView.dequeueReusableCell(withIdentifier: "sectionCell", for: indexPath) as! ShowHideSectionTableViewCell

            let sectionIndex = determineTrueIndexForSectionCellWith(cellIndex: indexPath.row)

            sectionCell.sectionLabel.text = "Section \(sectionIndex)"

            if indexPath.row+1 == visibleQuestionRowsArray.count {
                sectionCell.expandIndicatorLabel.text = "+"
            } else if visibleQuestionRowsArray[indexPath.row+1] == 0 {
                sectionCell.expandIndicatorLabel.text = "+"
            } else {
                sectionCell.expandIndicatorLabel.text = "-"
            }

            return sectionCell
        //Value 1 = content cell
        case 1:
            let contentCell = tableView.dequeueReusableCell(withIdentifier: "contentCell", for: indexPath) as! SectionContentTableViewCell

            let parentIndex = determineParentForContentCellWith(cellIndex: indexPath.row, currentSegment: currentSegment)

            contentCell.contentDelegate = self
            contentCell.contentSection = parentIndex


            contentCell.htmlString = questionHTMLStringsArray[parentIndex]

            //Check if height already recorded (therefore webview already instantiated)
            let checkOpen = contentHeights.filter({$0.segment == currentSegment && $0.section == parentIndex && $0.width == currentViewWidth})

            if checkOpen.isEmpty == true {
                print("webView instantiated")
                contentCell.webView = WKWebView(frame: CGRect(x: 0, y: 0, width: contentCell.frame.width, height: 44.0), configuration: WKWebViewConfiguration())
                contentCell.contentView.addSubview(contentCell.webView!)
            }

            contentCell.configureWebView()

            return contentCell
        default:
            return UITableViewCell()
        }

同步加载UITableViewCells

0 个答案: