使用消息更新 swift iOS 上的 TableViewCell

Question

这就是我的视图控制器中的内容。非常简单，有一个发送按钮和一个带有约束和 table 视图的消息字段。

import UIKit

class ViewController: UIViewController {

public let identifier = "ViewController"

private let tableView: UITableView = {
    let table = UITableView()
    table.register(SecureTextViewCell.self, forCellReuseIdentifier: SecureTextViewCell.identifier)
    return table
    
}()


private let secureButton : UIButton = {
    let button = UIButton()
    button.setTitle("Secure", for: .normal)
    button.backgroundColor = .link
    button.setTitleColor(.white, for: .normal)
    button.layer.cornerRadius = 12
    button.titleLabel?.font = .systemFont(ofSize: 20, weight: .bold)
    button.layer.masksToBounds = true
    button.addTarget( self, action: #selector(securebuttonTapped), for: .touchUpInside)
    return button
    
}()


let sendButton : UIButton = {
    let button = UIButton()
    button.setTitle("Send", for: .normal)
    button.backgroundColor = .green
    button.setTitleColor(.white, for: .normal)
    button.layer.cornerRadius = 12
    button.titleLabel?.font = .systemFont(ofSize: 20, weight: .bold)
    button.layer.masksToBounds = true
    button.addTarget( self, action: #selector(sendButtonTapped), for: .touchUpInside)
    return button
}()

let textView : UITextField = {
    let text = UITextField()
    text.isHidden = true
    text.isSecureTextEntry = true
    text.backgroundColor = .red
    text.isUserInteractionEnabled = false
    return text
}()

private let messageField: UITextField = {
    let field = UITextField()
    field.autocapitalizationType = .none
    field.autocorrectionType = .no
    field.returnKeyType = .done
    field.layer.cornerRadius = 12
    field.layer.borderWidth = 1
    field.layer.borderColor = UIColor.lightGray.cgColor
    field.placeholder = "Secure Text Message"
    field.leftViewMode = .always
    field.backgroundColor = .white
    field.isOpaque = true
    field.clearButtonMode = .always
    return field
}()
var passwordFieldConstraints : NSLayoutConstraint!
var sendButtonFieldCoonstraints: NSLayoutConstraint!

override func viewDidLoad() {
    super.viewDidLoad()
    
    tableView.delegate = self
    tableView.dataSource = self
    view.addSubview(tableView)
    view.addSubview(messageField)
    view.addSubview(sendButton)
    
    messageField.translatesAutoresizingMaskIntoConstraints = false
    sendButton.translatesAutoresizingMaskIntoConstraints = false
    messageField.addTarget(self, action: #selector(buttonAction), for: .touchUpInside)
    sendButton.heightAnchor.constraint(equalToConstant: 40).isActive = true
    sendButton.widthAnchor.constraint(equalTo: tableView.widthAnchor).isActive = true
    

    messageField.heightAnchor.constraint(equalToConstant: 40).isActive = true
    messageField.widthAnchor.constraint(equalTo: tableView.widthAnchor).isActive = true
}

override func viewDidLayoutSubviews() {
    super.viewDidLayoutSubviews()

    tableView.frame = view.bounds
    textView.frame = CGRect(x: 0, y: 300, width: view.width, height: 30)
}

@objc func sendButtonTapped() {
    
    print("send button tapped")
}


}


extension ViewController: UITableViewDelegate, UITableViewDataSource {
func tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
    
    return 5
 }
 func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) ->           UITableViewCell {
    let text = messageField.text!
    let cell = tableView.dequeueReusableCell(withIdentifier: TextViewCell.identifier, for: indexPath) as! TextViewCell
    cell.configure(with: text)
    return cell
    
}
func tableView(_ tableView: UITableView, heightForRowAt indexPath: IndexPath) -> CGFloat {
    return 80
}
}

这是我的 tableViewCell，应该使用我在消息字段中的文本进行更新？

import Foundation
import UIKit

class TextViewCell: UITableViewCell {

static let identifier = "SecureTextViewCell"


let secureText : UITextField = {
    let secureText = UITextField()
    secureText.text = ""
    secureText.isUserInteractionEnabled = false
    secureText.backgroundColor = .link
    return secureText
}()

override init(style: UITableViewCell.CellStyle, reuseIdentifier: String?) {
    super .init(style: style, reuseIdentifier: reuseIdentifier)
    
    contentView.addSubview(secureText)
}

required init?(coder: NSCoder) {
    fatalError("init(coder:) has not been implemented")
}

override func layoutSubviews() {
    super.layoutSubviews()
    contentView.addSubview(secureText)
    secureText.frame = CGRect(x: 0,
                                 y: 0,
                                 width: contentView.width,
                                 height: contentView.height)
}

public func configure(with model: String) {
    self.secureText.text = model
    
}
}

当我点击发送按钮时，我希望我的手机更新并显示我发送的消息。我不知道在我的发送按钮功能中放了什么，或者我是否以不同的方式处理这个问题。

我尝试了一些点击发送按钮的方法。在 table 视图 cellForRowAt 我也尝试过。

我很抱歉问了一个对大多数程序员来说可能很简单的问题。我是新人。

Answer 1

首先，您不应将文本字段添加到 layoutSubviews 中的单元格子视图，因为每次需要更新单元格的布局时都会调用它。根据 documentation 你应该只在那里放置代码来更新不能自动更新的子视图的布局：

Subclasses can override this method as needed to perform more precise layout of their subviews. You should override this method only if the autoresizing and constraint-based behaviors of the subviews do not offer the behavior you want. You can use your implementation to set the frame rectangles of your subviews directly.

因此请将您单元格中的 layoutSubviews 函数更新为：

override func layoutSubviews() {
   super.layoutSubviews()
   secureText.frame = contentView.bounds
}

现在从视图控制器更改单元格的文本可能就这么简单：

@objc func sendButtonTapped() {
    tableView.reloadData()
}

这将重新加载 table 的所有可见单元格，因为您已经在 tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell 中设置了文本配置，每个单元格都会显示您的消息字段的文本。

如果您只想更新一个特定的单元格，您需要更改单元格配置逻辑，然后为确切的单元格调用重新加载：

@objc func sendButtonTapped() {
    let indexPath = IndexPath(row: 0, section: 0) //index of cell to reload
    tableView.reloadRows(at: [indexPath], with: .automatic)
}

使用消息更新 swift iOS 上的 TableViewCell

Updating the TableViewCell on swift iOS with a message

ios

swift

uitableview

viewcontroller