NSLayoutConstraints 限制标签宽度

Question

我正在努力设置必要的约束以将标签的宽度限制为 tableview 单元格中按钮的前导锚点。

想要的结果

标签在左边，按钮在右边。如果需要，标签会在按钮前换行。

当前结果

标签将红色按钮拉向左侧。

代码

[button.centerYAnchor constraintEqualToAnchor:cell.contentView.centerYAnchor constant:0].active = YES;
[button.trailingAnchor constraintEqualToAnchor:cell.contentView.trailingAnchor constant:-5].active = YES;

[label.leadingAnchor constraintEqualToAnchor:cell.contentView.leadingAnchor constant:10].active = YES;
[label.trailingAnchor constraintEqualToAnchor:button.leadingAnchor constant:0].active = YES;

我已经尝试了各种方法，比如在单元格右侧添加另一个标签约束，但挤压了按钮（我试图通过设置其压缩阻力优先级来修复，但没有效果）

请问我需要什么约束才能达到预期的结果？

Answer 1

只是改变

[label.trailingAnchor constraintEqualToAnchor:button.leadingAnchor constant:0].active = YES;

进入

[label.trailingAnchor constraintLessThanOrEqualToAnchor:button.leadingAnchor constant:0].active = YES;

import UIKit

final class ViewController: UIViewController {

  lazy var tableView: UITableView = {
    let val = UITableView(frame: self.view.bounds, style: .plain)
    val.dataSource = self
    val.delegate = self
    val.estimatedRowHeight = 44
    val.register(MyCell.self, forCellReuseIdentifier: "MyCell")
    return val
  }()

  let data: [String] = [
    "LayoutDemo",
    "LayoutDemo LayoutDemo LayoutDemo LayoutDemo LayoutDemo LayoutDemo LayoutDemo LayoutDemo LayoutDemo LayoutDemo LayoutDemo LayoutDemo",
    "LayoutDemoLayoutDemoLayoutDemoLayoutDemo"
  ]

  override func viewDidLoad() {
    super.viewDidLoad()

    view.addSubview(tableView)
  }

}

extension ViewController: UITableViewDataSource {
  func tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
    data.count
  }

  func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
    guard let cell = tableView.dequeueReusableCell(withIdentifier: "MyCell", for: indexPath) as? MyCell else { fatalError() }
    cell.dataText = data[indexPath.row]
    return cell
  }

}

extension ViewController: UITableViewDelegate {

  func tableView(_ tableView: UITableView, heightForRowAt indexPath: IndexPath) -> CGFloat {
    return UITableView.automaticDimension
  }

}

class MyCell: UITableViewCell {

  var dataText: String? {
    didSet {
      label.text = dataText
    }
  }

  lazy var label: UILabel = {
    let val = UILabel(frame: .zero)
    val.translatesAutoresizingMaskIntoConstraints = false
    val.numberOfLines = 0
    val.backgroundColor = .gray
    return val
  }()

  lazy var button: UIButton = {
    let val = UIButton(type: .custom)
    val.translatesAutoresizingMaskIntoConstraints = false
    val.backgroundColor = .red
    return val
  }()

  override init(style: UITableViewCell.CellStyle, reuseIdentifier: String?) {
    super.init(style: style, reuseIdentifier: reuseIdentifier)

    contentView.addSubview(label)
    contentView.addSubview(button)

    NSLayoutConstraint.activate([
      button.centerYAnchor.constraint(equalTo: contentView.centerYAnchor),
      button.trailingAnchor.constraint(equalTo: contentView.trailingAnchor, constant: -5),
      button.heightAnchor.constraint(equalToConstant: 20),
      button.widthAnchor.constraint(equalToConstant: 20),

      label.topAnchor.constraint(equalTo: contentView.topAnchor, constant: 5),
      label.bottomAnchor.constraint(equalTo: contentView.bottomAnchor, constant: -5),
      label.leadingAnchor.constraint(equalTo: contentView.leadingAnchor, constant: 10),
      label.trailingAnchor.constraint(lessThanOrEqualTo: button.leadingAnchor, constant: -10)
    ])

  }

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

}

NSLayoutConstraints 限制标签宽度

NSLayoutConstraints to limit label width

objective-c

ios

autolayout