我有表格视图，并从xib取得了自定义单元格，我有很多
有媒体或较大的文本时，单元格中要扩展的事物的数量
在委托方法中以编程方式管理了高度
以及单元格中的约束，但是有时候我打开应用程序
加载数据时，单元格会重叠，但是当我上下滚动时，
看起来不错。我该怎么做才能在之后立即更新
从API获取数据时重新加载？
我认为代码中没有问题，因为它可以在再次刷新或滚动表视图后工作。
高度委托方法如下：
func tableView(_ tableView: UITableView, heightForRowAt indexPath: IndexPath) -> CGFloat {
let newsDict = self.tableDataNewsArray[indexPath.section]
let newsDataArray = newsDict["news"] as! [NewsBriefModel]
let newsObject = newsDataArray[indexPath.item]
if (self.moreExpandableArray.firstIndex(of: newsObject.newsbrief_id) != nil) {
return 62 + 58 + 4 + 62 //(62:// label minimum height )(46: other than label caponents in cell :: 4: spacing
// 62: more/less button view height)
}else if (self.lessExpandableArray.firstIndex(of: newsObject.newsbrief_id) != nil) {
var baseMoreHeight : CGFloat = newsObject.labelHeightForPostText + 58 + 4 + 62 //(46: other than label caponents in cell :: 4: spacing
// 62: more/less button view height)
if newsObject.numberOfImagesInPost > 0 {
baseMoreHeight = baseMoreHeight + 110
}
if newsObject.numberOfDocumentInPost > 0 {
baseMoreHeight = baseMoreHeight + CGFloat((newsObject.numberOfDocumentInPost * 45))
}
if newsObject.numberOfVideosInPost > 0 {
baseMoreHeight = baseMoreHeight + CGFloat((newsObject.numberOfVideosInPost * 100))
}
return baseMoreHeight
}
}
我在cellForRow中调用的Cell方法来更改UI：
// MARK: CELL METHODS
func showNormalView() {
self.postTitleLabel.numberOfLines = 3
self.postTitleTextView.textContainer.maximumNumberOfLines = 3
self.postTitleTextView.textContainer.lineBreakMode = .byTruncatingTail
self.mediaViewHeight.constant = 0
self.documentTableViewHeight.constant = 0
self.videoTableViewHeight.constant = 0
self.multiMediaView.isHidden = true
self.loadImages(urlString: [])
self.updateConstraintsIfNeeded()
self.setNeedsLayout()
self.layoutIfNeeded()
}
func showMoreView() {
self.postTitleLabel.numberOfLines = 3
self.postTitleTextView.textContainer.maximumNumberOfLines = 3
self.postTitleTextView.textContainer.lineBreakMode = .byTruncatingTail
self.mediaViewHeight.constant = 50
self.imageGridViewHeight.constant = 0
self.documentTableViewHeight.constant = 0
self.videoTableViewHeight.constant = 0
self.loadImages(urlString: [])
self.multiMediaView.isHidden = false
self.updateConstraintsIfNeeded()
self.setNeedsLayout()
self.layoutIfNeeded()
}
最佳答案
我建议使用UITableView.automaticDimension而不是手动计算高度，并使用委托模式来更新单元格的高度。
这是我使用这种方法的结果：
和代码示例：
import UIKit
struct Content {
let author: String
let date: String
let views: UInt
let recs: UInt
let content: String
}
let longText = """
Lorem ipsum dolor sit amet, consectetur adipiscing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua. Ut enim ad minim veniam, quis nostrud exercitation ullamco laboris nisi ut aliquip ex ea commodo consequat. Duis aute irure dolor in reprehenderit in voluptate velit esse cillum dolore eu fugiat nulla pariatur. Excepteur sint occaecat cupidatat non proident, sunt in culpa qui officia deserunt mollit anim id est laborum.
"""
protocol MyCellDelegate: AnyObject {
func contentDidChange(cell: UITableViewCell)
}
final class MyCell: UITableViewCell {
static let reuseIdentifier = "MyCell"
weak var delegate: MyCellDelegate?
private var viewsCountLabel: UILabel!
private var recsLabel: UILabel!
private var authorLabel: UILabel!
private var dateLabel: UILabel!
private var contentLabel: UILabel!
private var toggleHeightButton: UIButton!
override init(style: UITableViewCell.CellStyle, reuseIdentifier: String?) {
super.init(style: style, reuseIdentifier: reuseIdentifier)
setupSubviews()
}
required init?(coder: NSCoder) {
fatalError("not implemented")
}
override func prepareForReuse() {
super.prepareForReuse()
viewsCountLabel.text = nil
recsLabel.text = nil
authorLabel.text = nil
dateLabel.text = nil
contentLabel.text = nil
contentLabel.numberOfLines = 2
}
public func setContent(_ content: Content) {
viewsCountLabel.text = "Views: \(content.views)"
recsLabel.text = "Recs: \(content.recs)"
authorLabel.text = content.author
dateLabel.text = content.date
contentLabel.text = content.content
}
private func setupSubviews() {
let leftStackView = createLeftStack()
let rightStackView = createRightStack()
let stackView = UIStackView(arrangedSubviews: [leftStackView, rightStackView])
stackView.axis = .horizontal
stackView.spacing = 5
stackView.alignment = .top
contentView.addSubview(stackView)
stackView.translatesAutoresizingMaskIntoConstraints = false
NSLayoutConstraint.activate([
stackView.leadingAnchor.constraint(equalTo: contentView.leadingAnchor, constant: 10),
stackView.trailingAnchor.constraint(equalTo: contentView.trailingAnchor, constant: -10),
stackView.topAnchor.constraint(equalTo: contentView.topAnchor, constant: 3),
stackView.bottomAnchor.constraint(equalTo: contentView.bottomAnchor, constant: -3)
])
}
private func createLeftStack() -> UIStackView {
let iconView = createIconView()
viewsCountLabel = createLabel()
recsLabel = createLabel()
let stackView = UIStackView(arrangedSubviews: [iconView, viewsCountLabel, recsLabel])
stackView.axis = .vertical
stackView.setCustomSpacing(4, after: iconView)
stackView.alignment = .leading
return stackView
}
private func createRightStack() -> UIStackView {
authorLabel = createLabel()
dateLabel = createLabel()
contentLabel = UILabel()
contentLabel.font = UIFont.systemFont(ofSize: 13, weight: .bold)
contentLabel.contentMode = .topLeft
toggleHeightButton = UIButton(type: .system)
toggleHeightButton.setTitle("Toggle", for: .normal)
toggleHeightButton.addTarget(self, action: #selector(expandDidTap), for: .touchUpInside)
toggleHeightButton.heightAnchor.constraint(equalToConstant: 30).isActive = true
let stackView = UIStackView(arrangedSubviews: [authorLabel, dateLabel, contentLabel, toggleHeightButton])
stackView.axis = .vertical
stackView.alignment = .leading
return stackView
}
private func createIconView() -> UIView {
let iconView = UIView()
iconView.backgroundColor = .blue
iconView.layer.cornerRadius = 4
iconView.layer.masksToBounds = true
let label = UILabel()
label.font = UIFont.systemFont(ofSize: 8)
label.numberOfLines = 2
label.text = "Upload Icon"
label.textAlignment = .center
label.textColor = .white
iconView.addSubview(label)
label.translatesAutoresizingMaskIntoConstraints = false
iconView.translatesAutoresizingMaskIntoConstraints = false
NSLayoutConstraint.activate([
label.leadingAnchor.constraint(equalTo: iconView.leadingAnchor, constant: 3),
label.trailingAnchor.constraint(equalTo: iconView.trailingAnchor, constant: -3),
label.topAnchor.constraint(equalTo: iconView.topAnchor, constant: 3),
label.bottomAnchor.constraint(equalTo: iconView.bottomAnchor, constant: -3),
iconView.heightAnchor.constraint(equalToConstant: 40),
iconView.widthAnchor.constraint(equalToConstant: 40)
])
return iconView
}
private func createLabel() -> UILabel {
let label = UILabel()
label.font = UIFont.systemFont(ofSize: 8, weight: .light)
label.numberOfLines = 1
return label
}
@objc func expandDidTap() {
let isExpand = contentLabel.numberOfLines != 0
if isExpand {
contentLabel.numberOfLines = 0
} else {
contentLabel.numberOfLines = 2
}
delegate?.contentDidChange(cell: self)
}
}
final class MyViewController: UIViewController, UITableViewDelegate, UITableViewDataSource {
private var tableView: UITableView {
view as! UITableView
}
private var data: [Content] = [] {
didSet {
tableView.reloadData()
}
}
override func loadView() {
let tableView = UITableView()
tableView.delegate = self
tableView.dataSource = self
tableView.register(MyCell.self, forCellReuseIdentifier: MyCell.reuseIdentifier)
view = tableView
}
override func viewDidLoad() {
DispatchQueue.main.asyncAfter(deadline: .now() + 1) {
self.data = [
Content(author: "Author1", date: "15:07", views: 2, recs: 1, content: longText),
Content(author: "Author2", date: "15:07", views: 2, recs: 1, content: longText),
Content(author: "Author3", date: "15:07", views: 2, recs: 1, content: longText),
Content(author: "Author1", date: "15:07", views: 2, recs: 1, content: longText)
]
}
}
func tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
data.count
}
func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
let cell = tableView.dequeueReusableCell(withIdentifier: MyCell.reuseIdentifier, for: indexPath) as! MyCell
cell.delegate = self
let content = data[indexPath.row]
cell.setContent(content)
return cell
}
func tableView(_ tableView: UITableView, didSelectRowAt indexPath: IndexPath) {
tableView.deselectRow(at: indexPath, animated: true)
}
}
extension MyViewController: MyCellDelegate {
func contentDidChange(cell: UITableViewCell) {
UIView.animate(withDuration: 0.2) {
self.tableView.beginUpdates()
self.tableView.endUpdates()
}
}
}