Swift：如何在写入时不断调整 UICollectionViewCell 高度以适应 UITextView？

Question

Swift：如何在写入时不断调整 UICollectionViewCell 高度以适应 UITextView？

the*_*ahl 7 uitextview ios uicollectionview uicollectionviewcell swift

下午好。

我已经在我的 iOS 应用程序的这个“功能”上苦苦挣扎了几个小时，我需要一些帮助。

问题：我应该如何实现，以便当用户输入UITextView尺寸的增加（仅底部边距）并且单元格增加其高度以UITextView同时动态适应？我不知道如何解决它。

研究： 经过一番搜索后，我发现在键入文本时动态更改单元格的高度，并重新加载包含的表格视图以调整大小以及您可以在选择时对 UITableViewCell 上的高度变化进行动画处理吗？我还阅读了https://developer.apple.com/documentation/uikit/uicollectionview但我觉得到目前为止我的快速知识不如这些帖子中的预期。

换句话说，我不知道如何为我的 UICollectionView 实现它。

UITextView我的代码现在看起来像这样（我在 EventsCell 中有更多 UI 元素，但将它们剪掉以节省空间，因此它只是我想要更改的底部边距）。我已经将 RootCell 设置delegate为我的UITextView，然后我打算在编辑时获取 textView 高度，以获得我想要的高度，但它不起作用。

细胞类别：

class EventsCell: UICollectionViewCell {
  override init(frame: CGRect) {
    super.init(frame: frame)
    backgroundColor = UIColor.white
    setupViews()


  }
  let textView: GrowingTextView = { // GrowingTextView is a cocoapod extending UITextView
    let rootCellDelegate = RootCell()
    let tv = GrowingTextView()
    tv.backgroundColor = .clear
    tv.allowsEditingTextAttributes = true
    tv.isScrollEnabled = false
    tv.font = UIFont(name: "Didot", size: 16)
    tv.textColor = .black
    tv.textContainerInset = UIEdgeInsetsMake(4, 4, 4, 6)
    tv.placeholder = "Write your event text here"
    tv.placeholderColor = UIColor.lightGray
    tv.autoresizingMask = .flexibleHeight
    tv.isUserInteractionEnabled = false
    tv.delegate = rootCellDelegate
    return tv
}()

let eventPlaceholderMarkImage: UIButton = {
    let iv = UIButton()
    let image = UIImage(named: "placeHolderEventTitleMark")
    iv.setImage(image, for: .normal)

    return iv
}()

func setupViews() {


    //MARK: - Constraints for EventsCell
    //horizontal
    addConstraintsWithFormat(format: "H:|-16-[v0(\(frame.width - 32))]-16-|", views: textView)
    addConstraintsWithFormat(format: "V:|-47-[v0]-16-|", views: textView)

    addConstraint(NSLayoutConstraint(item: eventPlaceholderMarkImage, attribute: .bottom, relatedBy: .equal, toItem: textView, attribute: .top, multiplier: 1, constant: -7))
    addConstraint(NSLayoutConstraint(item: eventPlaceholderMarkImage, attribute: .height, relatedBy: .equal, toItem: self, attribute: .height, multiplier: 0, constant: 20))
    addConstraintsWithFormat(format: "H:|-12-[v0(27)]-\(cellWidth - 39)-|", views: eventPlaceholderMarkImage)
}
}

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UICollectionView类：

class RootCell: BaseCell, UICollectionViewDelegate, UICollectionViewDataSource, UICollectionViewDelegateFlowLayout {

      var textViewHeight : CGFloat?

func textViewDidChange(_ textView: UITextView) {
    textViewHeight = textView.textContainer.size.height + 63
    collectionView.reloadInputViews()
    collectionView.reloadData()
    collectionView.layoutSubviews()


}

  lazy var collectionView: UICollectionView = {
      let layout = UICollectionViewFlowLayout()
      let cv = UICollectionView(frame: .zero, collectionViewLayout: layout)
      cv.backgroundColor = UIColor.white
      cv.delegate = self
      cv.dataSource = self
      return cv
  }()

override func setupViews() {
    super.setupViews()

    addSubview(collectionView)
    addConstraintsWithFormat(format: "H:|[v0]|", views: collectionView)
    addConstraintsWithFormat(format: "V:|[v0]|", views: collectionView)

    collectionView.register(EventsCell.self, forCellWithReuseIdentifier: EventCellID)
}

func collectionView(_ collectionView: UICollectionView, numberOfItemsInSection section: Int) -> Int {
    return 10
}

func collectionView(_ collectionView: UICollectionView, cellForItemAt indexPath: IndexPath) -> UICollectionViewCell {
    let cell = collectionView.dequeueReusableCell(withReuseIdentifier: EventCellID, for: indexPath)
    return cell
}



func collectionView(_ collectionView: UICollectionView, layout collectionViewLayout: UICollectionViewLayout, sizeForItemAt indexPath: IndexPath) -> CGSize {

    let height = textViewHeight ?? frame.width * 1/3
    let width = frame.width - 8
    return CGSize(width: width, height: height)
}

func collectionView(_ collectionView: UICollectionView, layout collectionViewLayout: UICollectionViewLayout, minimumLineSpacingForSectionAt section: Int) -> CGFloat {
    return 0
}

//MARK: - Design selected cells background

func collectionView(_ collectionView: UICollectionView, didSelectItemAt indexPath: IndexPath) {

    if let cell = collectionView.cellForItem(at: indexPath) as? EventsCell {

        cell.textView.isUserInteractionEnabled = true
        cell.eventTitleLabel.isUserInteractionEnabled = true

        cell.layer.borderColor = UIColor.flatBlack.cgColor
        cell.layer.borderWidth = 2
        cell.layer.cornerRadius = 7
        cell.backgroundColor = GradientColor(.topToBottom, frame: cell.frame, colors: [UIColor.flatRed.withAlphaComponent(0.2), UIColor.white])


    } else {return}

}

func collectionView(_ collectionView: UICollectionView, didDeselectItemAt indexPath: IndexPath) {

    if let cell = collectionView.cellForItem(at: indexPath) {
        cell.layer.borderColor = UIColor.clear.cgColor
        cell.layer.borderWidth = 0
        cell.layer.cornerRadius = 0
        cell.backgroundColor = .white
    } else {return}

}
}

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第一次回答后尝试：

class RootCell: BaseCell, UITextViewDelegate, UICollectionViewDelegate, UICollectionViewDataSource, UICollectionViewDelegateFlowLayout {

var textViewText : String?

func textViewDidChange(_ textView: UITextView) {

    textViewText = textView.text
    DispatchQueue.main.async {
        self.collectionView.reloadInputViews()
        self.collectionView.reloadData()
    }


}

func heightWithConstrainedWidth(width: CGFloat, font: UIFont) -> CGFloat {

    let constraintRect = CGSize(width: width, height: CGFloat.greatestFiniteMagnitude)
    guard let boundingBox = textViewText?.boundingRect(with: constraintRect, options: [NSStringDrawingOptions.usesLineFragmentOrigin], attributes: [NSAttributedStringKey.font: font], context: nil) else {return frame.width * 1/3}

    return boundingBox.height
}

func collectionView(_ collectionView: UICollectionView, layout collectionViewLayout: UICollectionViewLayout, sizeForItemAt indexPath: IndexPath) -> CGSize {

    let width = frame.width - 8
    let height = heightWithConstrainedWidth(width: width, font: UIFont(name: "Didot", size: 16)!)
    return CGSize(width: width, height: height)

}

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感谢您阅读我的帖子！

Answer 1

den*_*niz 5

重新加载集合视图或单个单元格将使单元格闪烁，并且用户在键入时将失去对 TextView 的焦点。如果用户失去焦点，他们必须再次单击 UITextView 才能继续输入。

当您检测到 UITextView 需要调整大小时，您可以使 CollectionView 的布局无效 - 如果您的自动布局参数全部正确，这将导致单元格大小被调整。请参阅下面的示例：

我有一个 UICollectionCell，里面只有 UITextView，并且 UITextView 上的滚动被禁用。使用 AutoLayout 将 UITextView 正确限制到单元格的所有边缘。最后，单元格也是 UITextView 的委托，如下所示：

class MyCollectionCell: UICollectionViewCell {
  @IBOutlet private weak var myTextView: UITextView!

  //this local variable will be used to determine if the intrinsic content size has changed or not
  private var textViewHeight: CGFloat = .zero
  ...
  ...
  override func awakeFromNib() {
   super.awakeFromNib()
   myTextView.delegate = self
  }
  ...
  ...
}

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使此单元格符合 UITextViewDelegate

extension MyCollectionCell: UITextViewDelegate { 

func textViewShouldBeginEditing(_ textView: UITextView) -> Bool {
  //this assumes that collection view already correctly laid out the cell
  //to the correct height for the contents of the UITextView
  //textViewHeight simply needs to catch up to it before user starts typing
  let fittingSize = textView.sizeThatFits(CGSize(width: myTextView.frame.width, height: CGFloat.greatestFiniteMagnitude))
  textViewHeight = fittingSize.height

  return true
}

func textViewDidChange(_ textView: UITextView) {
  //flag to determine whether textview's size is changing
  var shouldResize = false
  //calculate fitting size after the content has changed
  let fittingSize = textView.sizeThatFits(CGSize(width: myTextView.frame.width, height: CGFloat.greatestFiniteMagnitude))

  //if the current height is not equal to the fitting height
  //save the new fitting height to our local variable and inform the delegate 
  //that collection view needs resizing
  if textViewHeight != fittingSize.height {
    shouldResize = true
    //save the new height 
    textViewHeight = fittingSize.height
  }

  //notify the cell's delegate (most likely a UIViewController) 
  //that UITextView's intrinsic content size has changed
  //perhaps with a protocol such as this:
  delegate?.textViewDidChange(newText: textView.text, alsoRequiresResize: shouldResize)
}

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然后，当委托收到通知时，可能会保存更新的文本并更新布局，如下所示：
```
myCollectionView.collectionViewLayout.invalidateLayout()
```
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该解决方案最好的部分是您不必调用 collectionView(_:layout:sizeForItemAt:)。

干杯!

Answer 2

小智 0

首先将textView文本存储在某个变量中，然后您可以通过此方法获取文本的高度

func heightWithConstrainedWidth(width: CGFloat, font: UIFont) -> CGFloat {
    let constraintRect = CGSize(width: width, height: CGFloat.greatestFiniteMagnitude)
    let boundingBox = self.boundingRect(with: constraintRect, options: [NSStringDrawingOptions.usesLineFragmentOrigin], attributes: [NSAttributedStringKey.font: font], context: nil)
    return boundingBox.height
}

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然后将其传入单元格的高度+您的填充，并且不要忘记collectionView在用户输入内容时重新加载您的内容

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