在 UITableViewCell 中加载的 Nib 文件 UIView 不会拉伸

问题描述

我有一个可通过 nib/xib 文件重复使用的 UIView.我想加载它并填充一个 UITableViewCell，它将用于自调整大小的 UITableView.全部自动布局.

I have a UIView which is reusable via a nib/xib-file. I want to load this and fill a UITableViewCell which is to be used in a self-resizing UITableView. All with auto-layout.

大多数效果很好，但似乎加载的 UIView 使用它周围添加的约束来缩小 UITableViewCell 的 contentView.这对高度有好处，但我不希望这样的宽度.

Most works good, but It seems as the loaded UIView uses the added constraints around it to shrink the UITableViewCell's contentView. This is good for the height, but I don't want this for the width.

忽略下面的灰色单元格，这只是一个选定的单元格.

Ignore the grey cell below, this is just a selected cell.

public func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell
{
    let cellId = "RowView0002"
    var cell = tableView.dequeueReusableCell(withIdentifier: cellId)
    if cell == nil {
        cell = UITableViewCell(style: UITableViewCellStyle.default, reuseIdentifier: cellId)

        let subView = RowView(frame: cell!.frame)

        cell!.contentView.attachViewWithConstraints(subView)
        let _ = subView.viewLoadedFromNibAttached(name: cellId)

    }

    return cell!
}

override public func viewDidLoad() {
    super.viewDidLoad()

    tableView.delegate = self
    tableView.dataSource = self
    tableView.estimatedRowHeight = 40.0
    tableView.rowHeight = UITableViewAutomaticDimension
}

extension UIView
{
    public func attachViewWithConstraints(_ view:UIView)
    {
        addSubview(view)
        view.translatesAutoresizingMaskIntoConstraints = false
        view.layoutAttachAll(to: self)
    }

    @discardableResult
    public func viewLoadedFromNibAttached<T : UIView>(name:String) -> T? {
        guard let view = Bundle.main.loadNibNamed(name, owner: self, options: nil)?[0] as? T else {
            return nil
        }
        attachViewWithConstraints(view)
        return view
    }

    public func layoutAttachAll(to childView:UIView)
    {
        var constraints = [NSLayoutConstraint]()

        childView.translatesAutoresizingMaskIntoConstraints = false
        constraints.append(NSLayoutConstraint(item: childView, attribute: .left, relatedBy: .equal, toItem: self, attribute: .left, multiplier: 1.0, constant: 0))
        constraints.append(NSLayoutConstraint(item: childView, attribute: .right, relatedBy: .equal, toItem: self, attribute: .right, multiplier: 1.0, constant: 0))
        constraints.append(NSLayoutConstraint(item: childView, attribute: .top, relatedBy: .equal, toItem: self, attribute: .top, multiplier: 1.0, constant: 0))
        constraints.append(NSLayoutConstraint(item: childView, attribute: .bottom, relatedBy: .equal, toItem: self, attribute: .bottom, multiplier: 1.0, constant: 0))

        childView.addConstraints(constraints)
    }

在 RowView0002.xib 中，我将 rootviews 背景设置为红色，并在其两侧添加了一个带有 4 个约束的 UILabel，并带有一些边距，如您所见.我都尝试将 rootView 设置为类 RowView 以及它的文件所有者.两者都有效".

In RowView0002.xib I have set the rootviews background to red, added a UILabel with 4 constraints to it's sides with some margin as you can see. I both tried to set the rootView to the class RowView as well as it's File's Owner. Both "works".

知道如何让 contentView 与 UITableView 匹配吗?

Any idea how to get the contentView to match the UITableView?

*绿色是 UILabel 的背景.红色是 nib 文件的背景.运行应用程序后，View heirarcy 是:UITableViewCell > ContentView > RowView > NibFileView (red) > UILabel (green)

*Edit 1: The green is the background of the UILabel. The red is the background of the nib-file. After running the app the View heirarcy is: UITableViewCell > ContentView > RowView > NibFileView (red) > UILabel (green)

检查视图层次结构表明所有约束都按预期设置.但是 UITableViewContentView 的约束与看到的总大小相匹配(错误):

Inspecting the view hierarchy shows that all constraints is setup as expected. However the UITableViewContentView have constraints that match the total size seen (wrong):

self.width = 156.5 @ 1000

推荐答案

我还通过添加与 tableViews 宽度匹配的宽度约束来解决它.这是来自 CustomTableViewCell 的代码:

I solved it by also adding a width constraint matching the tableViews width. This is code from CustomTableViewCell:

public override func layoutSubviews() {
    super.layoutSubviews()

    if let width = tableView()?.frame.width, !haveAddedWidthConstraint {
        haveAddedWidthConstraint = true
        rowView.addWidthConstraint(width: width)
    }
}

UIViewExtension:

UIViewExtension:

public func addWidthConstraint(width: CGFloat) {
    let widthConstraint = NSLayoutConstraint(item: self, attribute: .width, relatedBy: .greaterThanOrEqual, toItem: nil, attribute: .notAnAttribute, multiplier: 1.0, constant: width)
    widthConstraint.priority = 1000
    addConstraint(widthConstraint)
}

UITableViewCellExtension:

UITableViewCellExtension:

func tableView() -> UITableView? {
    var currentView: UIView = self
    while let superView = currentView.superview {
        if superView is UITableView {
            return (superView as! UITableView)
        }
        currentView = superView
    }
    return nil
}

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