ios - 带有 tableFooterView 的空 UITableView

Question

我有一个 UITableView，我想在其中 dataSource 为空时显示一条消息。我通过使用以下扩展设置背景 View 的众所周知的方法来做到这一点:

extension UITableView {

    func setEmptyMessage(_ message: String, _ image: String) {
        let emptyView: UIView = {
            let emptyView = UIView(frame: CGRect(x: 0, y: 0, width: self.frame.size.width, height: self.frame.size.height))
            return emptyView
        }()

        let contentView: UIView = {
            let contentView = UIView()
            contentView.translatesAutoresizingMaskIntoConstraints = false
            return contentView
        }()

        let messageLabel = UILabel()
        let messageCommentStyle = NSMutableParagraphStyle()
        messageCommentStyle.lineHeightMultiple = 1.2

        let attributedString = NSMutableAttributedString(string: message)
        attributedString.addAttribute(NSAttributedString.Key.foregroundColor, value: lightFeedUserNameFontColor, range: NSRange(location: 0, length: attributedString.length))
        attributedString.addAttribute(NSAttributedString.Key.paragraphStyle, value: messageCommentStyle, range: NSRange(location: 0, length: attributedString.length))
        attributedString.addAttribute(NSAttributedString.Key.font, value: UIFont.systemFont(ofSize: normalFontSize), range: NSRange(location: 0, length: attributedString.length))

        messageLabel.attributedText = attributedString
        messageLabel.numberOfLines = 0
        messageLabel.font = UIFont.systemFont(ofSize: normalFontSize)
        messageLabel.textAlignment = .center
        messageLabel.sizeToFit()
        messageLabel.translatesAutoresizingMaskIntoConstraints = false

        let errorImage: UIImageView = {
            let errorImage = UIImageView()
            errorImage.translatesAutoresizingMaskIntoConstraints = false
            return errorImage
        }()

        self.backgroundView = emptyView

        emptyView.addSubview(contentView)
        contentView.addSubview(errorImage)
        contentView.addSubview(messageLabel)

        contentView.centerYAnchor.constraint(equalTo: emptyView.centerYAnchor).isActive = true
        contentView.centerXAnchor.constraint(equalTo: emptyView.centerXAnchor).isActive = true
        contentView.leadingAnchor.constraint(equalTo: emptyView.leadingAnchor, constant: normalSpacing * 3).isActive = true
        contentView.trailingAnchor.constraint(equalTo: emptyView.trailingAnchor, constant: -(normalSpacing * 3)).isActive = true
        contentView.topAnchor.constraint(equalTo: errorImage.topAnchor).isActive = true
        contentView.bottomAnchor.constraint(equalTo: messageLabel.bottomAnchor).isActive = true

        messageLabel.leadingAnchor.constraint(equalTo: contentView.leadingAnchor).isActive = true
        messageLabel.trailingAnchor.constraint(equalTo: contentView.trailingAnchor).isActive = true
        messageLabel.centerYAnchor.constraint(equalTo: contentView.centerYAnchor).isActive = true
    }

    func restore() {
        self.backgroundView = nil
    }
}

我这样设置:

if(tableData.isEmpty) {
    self.tableView.setEmptyMessage("No results!", "none")
} else {
    self.tableView.restore()
}

self.tableView.reloadData()

没什么大不了的，我们都见过这个并且可能使用过它。而且效果很好。但是，我现在在 tableFooterView 底部放置了一个 UIButton 。该按钮位于 UITableView 的顶部，因为它会自动将自己定位在最后一个单元格的正下方，这正是我在有数据时想要的，但现在空消息显示在屏幕中间当按钮位于其上方时。我该如何解决这个问题，以便在数据源为空时出现某种框架？

举例说明:

Answer 1

所以现在您将 tableView 背景 View 设置为空 View 。您可以查看您的数据源，如果它是空的 - 只需使用此消息返回空状态的新单元格。

func tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
    return dataSource.count > 0 ? dataSource.count : 1
}

func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
    if dataSource.count.isEmpty 0 {
        let cell = tableView.dequeueReusableCell(withIdentifier: "EmptyCell")
        cell.textLabel.text = "No Results!"
        return cell
    } else {
        let cell = tableView.dequeueReusableCell(withIdentifier: "SomeCell")
        return cell
    }
}