'*** -[__NSArrayM insertObject:atIndex:]: object cannot be nil' 执行 UITableView 动画重载时答案

【问题标题】：'*** -[__NSArrayM insertObject:atIndex:]: object cannot be nil' when performing UITableView animated reload'*** -[__NSArrayM insertObject:atIndex:]: object cannot be nil' 执行 UITableView 动画重载时
【发布时间】：2016-04-07 07:55:02
【问题描述】：

问题摘要：当我在我的UITableView 中有很多单元格时，当我从UITextView 编辑它的文本时为UITableViewCell 的高度设置动画时，它会崩溃。使用 iOS 8 自动调整大小的单元格。

长问题：我已经成功实现，所以我可以使用 iOS 8 自动调整大小的单元格在 UITextView 单元格中动态输入文本并更改单元格高度而不会失去焦点（firstReponder）。但是，如果 tableView 太大（有太多行）它会崩溃。这是我的堆栈跟踪：

Terminating app due to uncaught exception 'NSInvalidArgumentException', reason: '*** -[__NSArrayM insertObject:atIndex:]: object cannot be nil'
*** First throw call stack:
(
0   CoreFoundation                      0x000000010b3b3d85 __exceptionPreprocess + 165
1   libobjc.A.dylib                     0x000000010b9cbdeb objc_exception_throw + 48
2   CoreFoundation                      0x000000010b274cc5 -[__NSArrayM insertObject:atIndex:] + 901
3   UIKit                               0x0000000108b05439 __46-[UITableView _updateWithItems:updateSupport:]_block_invoke1029 + 180
4   UIKit                               0x0000000108a7e838 +[UIView(UIViewAnimationWithBlocks) _setupAnimationWithDuration:delay:view:options:factory:animations:start:animationStateGenerator:completion:] + 582
5   UIKit                               0x0000000108a7ec6d +[UIView(UIViewAnimationWithBlocks) animateWithDuration:delay:options:animations:completion:] + 105
6   UIKit                               0x0000000108b05048 -[UITableView _updateWithItems:updateSupport:] + 4590
7   UIKit                               0x0000000108afd5a0 -[UITableView _endCellAnimationsWithContext:] + 15360
8   Test RYM                            0x0000000107e6a173 _TFE8Test_RYMCSo11UITableView31reloadDataAnimatedKeepingOffsetfT_T_ + 163
9   Test RYM                            0x0000000107e6a242 _TToFE8Test_RYMCSo11UITableView31reloadDataAnimatedKeepingOffsetfT_T_ + 34
10  Test RYM                            0x0000000107dcda90 _TFC8Test_RYM20AgendaViewController19cellHeightDidUpdatefTCSo11NSIndexPath6heightV12CoreGraphics7CGFloat_T_ + 144
11  Test RYM                            0x0000000107dcdb04 _TToFC8Test_RYM20AgendaViewController19cellHeightDidUpdatefTCSo11NSIndexPath6heightV12CoreGraphics7CGFloat_T_ + 68
12  Test RYM                            0x0000000107e725cb _TFC8Test_RYM27AgendaDecisionTableViewCell20updateTextViewHeightfT_T_ + 907
13  Test RYM                            0x0000000107e731fa _TFC8Test_RYM27AgendaDecisionTableViewCell17textViewDidChangefCSo10UITextViewT_ + 42

以及导致它的代码：

// In UITableView extension
func reloadDataAnimatedKeepingOffset() {
    //let offset = contentOffset
    //UIView.setAnimationsEnabled(false)
    beginUpdates()
    endUpdates()
    //UIView.setAnimationsEnabled(true)
    //layoutIfNeeded()
    //contentOffset = offset
}

// In a self-sizing UITableViewCell subclass
func updateTextViewHeight() {
    let size = decisionTextView.bounds.size
    let newSize = decisionTextView.sizeThatFits(CGSize(width: size.width, height: CGFloat.max))
    let newHeight = newSize.height
    if size.height != newHeight {
        textViewHeightConstraint.constant = newHeight
        agendaViewController?.cellHeightDidUpdate(indexPath!, height: newSize.height)
    }
}

// In the ViewController managing the tableView
public func cellHeightDidUpdate(indexPath: NSIndexPath, height: CGFloat) {
    updateHelperAlphas()
    tableView?.reloadDataAnimatedKeepingOffset()
}

它在调用endUpdates() 时崩溃。我试图删除UITableView insertRowsAtIndexPaths throwing __NSArrayM insertObject:atIndex:'object cannot be nil' error中提到的tableView:estimatedHeightForRowAtIndexPath:方法，但没有成功。

它似乎也只在列表很长时才会发生。

编辑：我使用的更多方法：

public func tableView(tableView: UITableView, estimatedHeightForRowAtIndexPath indexPath: NSIndexPath) -> CGFloat {
    return 48.0
}

public func tableView(tableView: UITableView, heightForHeaderInSection section: Int) -> CGFloat {
    if (section == 0) {
        return 0
    }
    else {
        let currentSectionIsEmpty = sectionIsEmpty(section)
        if ((!isInEditProtocolMode && isProtocolMode) || isPreviousProtocolMode) && currentSectionIsEmpty {
            return 0
        }
        let subSection = sectionHelper.subSectionForSection(section)
        let isProtocolTopSection = isProtocolMode && subSection == 0
        if (isProtocolTopSection) {
            return UITableViewAutomaticDimension
        }
        else {
            return agendaHeaderHeight
        }
    }
}

public func tableView(tableView: UITableView, estimatedHeightForHeaderInSection section: Int) -> CGFloat {
    if (section == 0) {
        return 0
    }
    else {
        let subSection = sectionHelper.subSectionForSection(section)
        let isProtocolTopSection = isProtocolMode && subSection == 0
        if (isProtocolTopSection) {
            return protocolAgendaHeaderHeight
        }
        else {
            return agendaHeaderHeight
        }
    }
}

public override func viewDidLoad() {
    super.viewDidLoad()
    tableView.rowHeight = UITableViewAutomaticDimension
}

编辑2： 这几乎是同样的问题。 tableView crashes on end up with more than 16 items 但是我无法删除单元格高度的估计，因为这会破坏我的自定尺寸单元格视图的动态高度。

编辑 3： 尝试（来自下面的 cmets）在没有任何帮助的情况下使用 CATransaction.setDisableActions(_) 和 setContentOffset(_:animated:)。这似乎与此无关，因为删除除 beginUpdates() 和 endUpdates() 之外的所有内容也无济于事。 reloadDataAnimatedKeepingOffset() 似乎只被调用一次，而没有其他reloadData 似乎同时被调用。将估计高度设置为 1 而不是 0 也无济于事。它奇怪地显示了第零节标题（不是高度 1）。

编辑 4： 根据要求，这里是我的 numberOrRowsInSection 和 cellForRowAtIndexPath 方法（有点复杂）：

public func tableView(tableView: UITableView, numberOfRowsInSection section: Int) -> Int
{
    let mainSection = sectionHelper.mainSectionForSection(section)
    let subSection = sectionHelper.subSectionForSection(section)


    let isHeaderSection = subSection <= 0
    if isHeaderSection {
        return isProtocolMode ? 0 : cellIdSectionList[0].count
    }

    let rowType = sectionHelper.rowTypeForSection(section)

    let agenda = agendaForSection(section)

    switch rowType {
    case .NoteRow:
        return mainSectionShowingPlaceholderNewNoteCell == mainSection || !agenda.protocolString.isEmpty ? 1 : 0
    case .ActionRow:
        let count = max(0, agenda.actionListCount())
        return count
    case .DecisionRow:
        var count = agenda.decisions.count ?? 0
        count = max(0, count)
        count = indexPathShowingPlaceholderNewDecisionCell?.section == section ? count+1 : count
        return count
    default:
        return 0
    }
}

public func tableView(tableView: UITableView, cellForRowAtIndexPath indexPath: NSIndexPath) -> UITableViewCell
{
    let row = indexPath.row
    let section = indexPath.section
    let cellId = cellIdForIndexPath(indexPath)

    let cell = tableView.dequeueReusableCellWithIdentifier(cellId, forIndexPath: indexPath)
    let allowEditing = (isInEditProtocolMode || !isProtocolMode) && !isPreviousProtocolMode

    if let titleCell = cell as? StandardTitleTableViewCell {
        titleCell.setup(agendaForSection(section), meeting:selectedMeeting!, indexPath:indexPath)
        titleCell.delegate = self
    }
    if let descriptionCell = cell as? StandardDescriptionTableViewCell {
        descriptionCell.setup(agendaForSection(section), meeting:selectedMeeting!, indexPath: indexPath, forceExpand: hasExpandedDescriptionCellView)
        descriptionCell.delegate = self
    }

    if let noteCell = cell as? AgendaNotesTableViewCell {
        noteCell.setup(agendaForSection(section), meeting:selectedMeeting!, indexPath: indexPath, allowEditing:allowEditing)
        noteCell.agendaViewController = self
    }

    if let decisionCell = cell as? AgendaDecisionTableViewCell {
        let decisionList = agendaForSection(section).decisions
        let isNewDecisionCell = row >= decisionList.count
        if !isNewDecisionCell {
            let decision = decisionList[row]
            decisionCell.setup(decision, meeting:selectedMeeting!, indexPath: indexPath, allowEditing: allowEditing)
        }
        else {
            decisionCell.setup(newDecisionToAdd!, meeting:selectedMeeting!, indexPath: indexPath, allowEditing: allowEditing)
        }
        decisionCell.agendaViewController = self
    }

    if let actionCell = cell as? StandardTableViewCell,
        let actionList = agendaForSection(section).actionList {
            let action = actionList.actions[row]
            actionCell.setupAsActionListCell(action:action, indexPath: indexPath, delegate: self)
    }

    if let textCell = cell as? MeetingTextTableViewCell {
        var placeholderText = ""
        if indexPathIsActionTextPlaceholderCell(indexPath) {
            placeholderText = __("agenda.noActions.text")
        }
        else if indexPathIsDecisionTextPlaceholderCell(indexPath) {
            placeholderText = __("agenda.noDecisions.text")
        }
        textCell.setup(placeholderText)
    }

    return cell
}

public func tableView(tableView: UITableView, viewForHeaderInSection section: Int) -> UIView?
{
    if (section == 0) {
        return nil
    }
    let subSection = sectionHelper.subSectionForSection(section)
    let cellId = isProtocolMode && subSection == 0 ? protocolHeaderCellId : headerCellId
    let cell = tableView.dequeueReusableHeaderFooterViewWithIdentifier(cellId)
    let agenda = agendaForSection(section)

    if let standardHeaderCell = cell as? StandardTableViewHeaderCell {
        let subSection = sectionHelper.subSectionForSection(section)

        let currentSectionIsEmpty = sectionIsEmpty(section)
        let protocolIsLocked = selectedMeeting!.protocolIsLocked
        if (isPreviousProtocolMode && currentSectionIsEmpty) {
            return nil
        }
        let allowEditing = (isInEditProtocolMode || !isProtocolMode) && !isPreviousProtocolMode && !protocolIsLocked
        let showRightAddButton = ((subSection == 1 && currentSectionIsEmpty) || subSection == 2 || (subSection == 3 && indexPathShowingPlaceholderNewDecisionCell?.section != section)) && allowEditing

        let headerTitle = headerTitleList[subSection]
        standardHeaderCell.setupWithText(headerTitle, section:section, showAddButton: showRightAddButton, delegate: self)
    }
    else if let protocolHeaderCell = cell as? ProtocolTableViewHeaderCell {
        let showSeparator = section > 1
        let onlyShowAttachmentIfItHaveAttachments = isPreviousProtocolMode || (isProtocolMode && !isInEditProtocolMode)
        let showAttachmentIcon = !onlyShowAttachmentIfItHaveAttachments || agenda.attachments.count > 0
        protocolHeaderCell.setup(showSeparator: showSeparator, agenda: agenda, section: section, showProtocolIcon: false, showAttachmentIcon: showAttachmentIcon, delegate: self)
    }

    return cell!.wrappedInNewView()
}

// In UIView extension
func wrappedInNewView() -> UIView
{
    let view = UIView(frame: frame)
    autoresizingMask = [.FlexibleHeight, .FlexibleWidth]
    view.addSubview(self)
    return view
}

【问题讨论】：

我认为您显示的任何代码中都没有异常。
您能否提供更多有关您的插入和正在处理数据的功能的详细信息
从 tableView 的数据源中添加了更多内容。我不做任何插入，只在输入文本时重新加载表格视图以更新单元格的高度。当高度发生变化并重新加载 tableview 时它会崩溃（endUpdates()）
@trojanfoe 调用beginUpdates(); endUpdates() 之间的任何内容是一种记录（在UITableView.beginUpdates() 文档中）更新单元格高度的方法。
你能创建一个最小的可编译示例并放在github上吗？

标签： ios uitableview

【解决方案1】：

这里是关于这个 iOS 错误的雷达：http://openradar.appspot.com/15729686 我能建议你做的就是替换这个：

public func tableView(tableView: UITableView, estimatedHeightForRowAtIndexPath indexPath: NSIndexPath) -> CGFloat {
    return 48.0
}

用这个：

tableView.rowHeight = UITableViewAutomaticDimension
tableView.estimatedRowHeight = 48.0

如果仍然崩溃，那么也尝试删除tableView:estimatedHeightForHeaderInSection:方法

我们应该祈祷，希望这个雷达将被新的iOS X 关闭:)

【讨论】：