Swift collectionView.reloadsection未重新加载单元格

所以我使用合成布局来自动调整单元格大小。这就是我创建布局部分的方式。然后在UICollectionViewCompositionLayout（sectionProvider:）中返回它

这部分看起来像这样

class WhatsNewCell: UICollectionViewCell {
  static let reuseIdentifier  = String(describing: WhatsNewCell.self)
  var delegate: WhatsNewCellDelegate?

  @IBOutlet weak var appVersionLabel: UILabel!
  @IBOutlet weak var appUpdateLabel: UILabel!
  @IBOutlet weak var moreButton: UIButton!


  override func awakeFromNib() {
    super.awakeFromNib()
    moreButton.addTarget(self, action: #selector(handleMore), for: .touchUpInside)
  }

  @objc private func handleMore() {
    self.moreButton.setTitle("", for: .normal)
    self.appUpdateLabel.numberOfLines = 0

    delegate?.moreButtonClick()
  }
}

var shouldShowFullDetails: Bool = false

func moreButtonClick() {
    model?.shouldShowFullDetails = true

    self.collectionView.reloadItems(at: [IndexPath(item: 0, section: 1)])
}

  class WhatsNewCell: UICollectionViewCell {
  static let reuseIdentifier  = String(describing: WhatsNewCell.self)
  var delegate: WhatsNewCellDelegate?

  @IBOutlet weak var appVersionLabel: UILabel!
  @IBOutlet weak var appUpdateLabel: UILabel!
  @IBOutlet weak var moreButton: UIButton!

  var model: Model? {
    didSet {
        configureCell()
    }
  }

  override func awakeFromNib() {
    super.awakeFromNib()

    moreButton.addTarget(self, action: #selector(handleMore), for: .touchUpInside)
  }

  @objc func handleMore() {
    delegate?.moreButtonClick()
  }

  private func configureCell() {
    guard let model = model else { return }

    if app.shouldShowFullReleaseNotes {
        appUpdateLabel.numberOfLines = 0
    } else {
        appUpdateLabel.numberOfLines = 3
      }
  }
}

现在我有2个nib文件，每个文件都有自己的类。节标题只有一个标签和一个按钮。让我们忽略标题，因为问题在于WhatsNewCell。类文件看起来像这样

class WhatsNewCell: UICollectionViewCell {
  static let reuseIdentifier  = String(describing: WhatsNewCell.self)
  var delegate: WhatsNewCellDelegate?

  @IBOutlet weak var appVersionLabel: UILabel!
  @IBOutlet weak var appUpdateLabel: UILabel!
  @IBOutlet weak var moreButton: UIButton!


  override func awakeFromNib() {
    super.awakeFromNib()
    moreButton.addTarget(self, action: #selector(handleMore), for: .touchUpInside)
  }

  @objc private func handleMore() {
    self.moreButton.setTitle("", for: .normal)
    self.appUpdateLabel.numberOfLines = 0

    delegate?.moreButtonClick()
  }
}

var shouldShowFullDetails: Bool = false

func moreButtonClick() {
    model?.shouldShowFullDetails = true

    self.collectionView.reloadItems(at: [IndexPath(item: 0, section: 1)])
}

  class WhatsNewCell: UICollectionViewCell {
  static let reuseIdentifier  = String(describing: WhatsNewCell.self)
  var delegate: WhatsNewCellDelegate?

  @IBOutlet weak var appVersionLabel: UILabel!
  @IBOutlet weak var appUpdateLabel: UILabel!
  @IBOutlet weak var moreButton: UIButton!

  var model: Model? {
    didSet {
        configureCell()
    }
  }

  override func awakeFromNib() {
    super.awakeFromNib()

    moreButton.addTarget(self, action: #selector(handleMore), for: .touchUpInside)
  }

  @objc func handleMore() {
    delegate?.moreButtonClick()
  }

  private func configureCell() {
    guard let model = model else { return }

    if app.shouldShowFullReleaseNotes {
        appUpdateLabel.numberOfLines = 0
    } else {
        appUpdateLabel.numberOfLines = 3
      }
  }
}

好的，版本标签和更新标签在堆栈视图中。当用户单击按钮时，我会更改更新标签的行数。现在我创建了一个名为WhatsNewCellDelegate的委托，以便能够从控制器重新加载我的集合视图。这就是我在控制器中重新加载集合视图的方式。当我初始化一个单元格时，我也把单元格委托给了我的控制器

extension AppDetailCollectionVC: WhatsNewCellDelegate {
func moreButtonClick() {
   //collectionView.collectionViewLayout.invalidateLayout()

    collectionView.performBatchUpdates({
        //collectionView.reloadData()
        collectionView.reloadSections(IndexSet(integer: 2))
    }, completion: nil)
}

}

现在，当我调用reloaddata时，它可以工作，但当我调用reloaddata时，它不工作。我必须按两次“更多”按钮，它才能处理重新加载部分。我也尝试使用invalidateLayout（），但它会使我的一些细胞消失。请看下面的屏幕截图

这是我使用invalidateLayout（）单击“更多”按钮时的外观

---

所以我不知道发生了什么。我怎样才能在不必按两次“更多”按钮的情况下重新加载该部分。非常感谢您的帮助。

尝试在主线程上运行它，而不使用

性能更新

DispatchQueue.main.async {
    collectionView.reloadSections(IndexSet(integer: 2))
}

所以我让它工作了。我必须在我的模型中添加一个属性。像这样的

class WhatsNewCell: UICollectionViewCell {
  static let reuseIdentifier  = String(describing: WhatsNewCell.self)
  var delegate: WhatsNewCellDelegate?

  @IBOutlet weak var appVersionLabel: UILabel!
  @IBOutlet weak var appUpdateLabel: UILabel!
  @IBOutlet weak var moreButton: UIButton!


  override func awakeFromNib() {
    super.awakeFromNib()
    moreButton.addTarget(self, action: #selector(handleMore), for: .touchUpInside)
  }

  @objc private func handleMore() {
    self.moreButton.setTitle("", for: .normal)
    self.appUpdateLabel.numberOfLines = 0

    delegate?.moreButtonClick()
  }
}

var shouldShowFullDetails: Bool = false

func moreButtonClick() {
    model?.shouldShowFullDetails = true

    self.collectionView.reloadItems(at: [IndexPath(item: 0, section: 1)])
}

  class WhatsNewCell: UICollectionViewCell {
  static let reuseIdentifier  = String(describing: WhatsNewCell.self)
  var delegate: WhatsNewCellDelegate?

  @IBOutlet weak var appVersionLabel: UILabel!
  @IBOutlet weak var appUpdateLabel: UILabel!
  @IBOutlet weak var moreButton: UIButton!

  var model: Model? {
    didSet {
        configureCell()
    }
  }

  override func awakeFromNib() {
    super.awakeFromNib()

    moreButton.addTarget(self, action: #selector(handleMore), for: .touchUpInside)
  }

  @objc func handleMore() {
    delegate?.moreButtonClick()
  }

  private func configureCell() {
    guard let model = model else { return }

    if app.shouldShowFullReleaseNotes {
        appUpdateLabel.numberOfLines = 0
    } else {
        appUpdateLabel.numberOfLines = 3
      }
  }
}

然后我不得不这样做

class WhatsNewCell: UICollectionViewCell {
  static let reuseIdentifier  = String(describing: WhatsNewCell.self)
  var delegate: WhatsNewCellDelegate?

  @IBOutlet weak var appVersionLabel: UILabel!
  @IBOutlet weak var appUpdateLabel: UILabel!
  @IBOutlet weak var moreButton: UIButton!


  override func awakeFromNib() {
    super.awakeFromNib()
    moreButton.addTarget(self, action: #selector(handleMore), for: .touchUpInside)
  }

  @objc private func handleMore() {
    self.moreButton.setTitle("", for: .normal)
    self.appUpdateLabel.numberOfLines = 0

    delegate?.moreButtonClick()
  }
}

var shouldShowFullDetails: Bool = false

func moreButtonClick() {
    model?.shouldShowFullDetails = true

    self.collectionView.reloadItems(at: [IndexPath(item: 0, section: 1)])
}

  class WhatsNewCell: UICollectionViewCell {
  static let reuseIdentifier  = String(describing: WhatsNewCell.self)
  var delegate: WhatsNewCellDelegate?

  @IBOutlet weak var appVersionLabel: UILabel!
  @IBOutlet weak var appUpdateLabel: UILabel!
  @IBOutlet weak var moreButton: UIButton!

  var model: Model? {
    didSet {
        configureCell()
    }
  }

  override func awakeFromNib() {
    super.awakeFromNib()

    moreButton.addTarget(self, action: #selector(handleMore), for: .touchUpInside)
  }

  @objc func handleMore() {
    delegate?.moreButtonClick()
  }

  private func configureCell() {
    guard let model = model else { return }

    if app.shouldShowFullReleaseNotes {
        appUpdateLabel.numberOfLines = 0
    } else {
        appUpdateLabel.numberOfLines = 3
      }
  }
}

然后在我的手机档案里我不得不做这样的事情

class WhatsNewCell: UICollectionViewCell {
  static let reuseIdentifier  = String(describing: WhatsNewCell.self)
  var delegate: WhatsNewCellDelegate?

  @IBOutlet weak var appVersionLabel: UILabel!
  @IBOutlet weak var appUpdateLabel: UILabel!
  @IBOutlet weak var moreButton: UIButton!


  override func awakeFromNib() {
    super.awakeFromNib()
    moreButton.addTarget(self, action: #selector(handleMore), for: .touchUpInside)
  }

  @objc private func handleMore() {
    self.moreButton.setTitle("", for: .normal)
    self.appUpdateLabel.numberOfLines = 0

    delegate?.moreButtonClick()
  }
}

var shouldShowFullDetails: Bool = false

func moreButtonClick() {
    model?.shouldShowFullDetails = true

    self.collectionView.reloadItems(at: [IndexPath(item: 0, section: 1)])
}

  class WhatsNewCell: UICollectionViewCell {
  static let reuseIdentifier  = String(describing: WhatsNewCell.self)
  var delegate: WhatsNewCellDelegate?

  @IBOutlet weak var appVersionLabel: UILabel!
  @IBOutlet weak var appUpdateLabel: UILabel!
  @IBOutlet weak var moreButton: UIButton!

  var model: Model? {
    didSet {
        configureCell()
    }
  }

  override func awakeFromNib() {
    super.awakeFromNib()

    moreButton.addTarget(self, action: #selector(handleMore), for: .touchUpInside)
  }

  @objc func handleMore() {
    delegate?.moreButtonClick()
  }

  private func configureCell() {
    guard let model = model else { return }

    if app.shouldShowFullReleaseNotes {
        appUpdateLabel.numberOfLines = 0
    } else {
        appUpdateLabel.numberOfLines = 3
      }
  }
}

如果你这么做会怎么样

extension AppDetailCollectionVC: WhatsNewCellDelegate {
    func moreButtonClick() {
         collectionView.collectionViewLayout.invalidateLayout()
    }
}

我想当您第一次重新加载节时，collectionView会创建新的单元格和
self.appUpdateLabel.numberOfLines
采用初始值
0
。
您可以在
awakeFromNib
中添加断点，然后点击“更多”按钮进行检查

尝试加载项方法
@objc private func handleMore（）
–
self.invalidateIntrinsicContentSize（）

正如Luis Ramirez所提到的，你们应该为电池使用一些外部配置

或者，如果在此集合视图中只有一个单元格的类型为
WhatsNewCell
，则可以执行以下操作：

class WhatsNewCell: UICollectionViewCell {
    private static var shouldShowDetails = false


  override func awakeFromNib() {
    super.awakeFromNib()
    if Self.shouldShowDetails {
        self.moreButton.setTitle("", for: .normal)
        self.appUpdateLabel.numberOfLines = 0
    } else {
        self.moreButton.addTarget(self, action: #selector(handleMore), for: .touchUpInside)
    }
  }

    @objc private func handleMore() {
        Self.shouldShowDetails = true
        ....
    }
}

我刚试过。我仍然需要点击“更多”按钮两次才能看到单元格重新加载。这会使我的一些单元格消失，我不知道为什么。请看屏幕截图，看看我使用invalidateLayout（）时会发生什么。简单地说，您的单元格存储的信息在另一个单元格退出队列时不会持久化。此外，它不会重置。您必须在控制器中存储有关“更多”的信息，并始终在单元格中更新这些信息。