下午好。
我已经为我的 iOS 应用的这个“功能”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，以便当用户在 UITextView 中键入时尺寸增加(仅底部边距)并且单元格增加其高度以适应UITextView 同时动态？我不知道如何解决它。
研究: 经过一番搜索，我找到了 Dynamically change cell's height while typing text, and reload the containing tableview for resize以及Can you animate a height change on a UITableViewCell when selected?我也读过 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。
我的代码现在看起来像这样(我在 EventsCell 中有更多的 UI 元素，但为了节省空间而将它们剪掉，因此它只是我想更改的 UITextView 的底部边距)。我已将 RootCell 设置为 UITextView 的 delegate 然后我打算在编辑时获取 textView 高度以获得我想要的高度，但它不是不工作。
细胞类:
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)
}
}
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}
}
}
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)
}
感谢您阅读我的文章!
最佳答案
重新加载 Collection View 或单个单元格会使单元格闪烁，并且用户在键入时会失去对 TextView 的关注。如果用户失去焦点，他们必须再次单击 UITextView 才能继续输入。
当您检测到您的 UITextView 需要调整大小时，您可以使您的 collectionview 的布局无效 - 如果您的自动布局参数全部正确，这将导致您的单元格调整大小。请参见下面的示例:
我有一个 UICollectionCell，其中只有 UITextView，并且在 UITextView 上滚动被禁用。使用 AutoLayout 将 UITextView 正确约束到单元格的所有边缘。最后，单元格本身也是 UITextView 的委托(delegate):
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 } ... ... }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) }然后当代理收到通知时，可能会保存更新的文本并更新布局，如下所示:
myCollectionView.collectionViewLayout.invalidateLayout()
此解决方案最好的部分是您不必调用 collectionView(_:layout:sizeForItemAt:)。
干杯!
关于ios - Swift:如何在写入时不断调整 UICollectionViewCell 高度以适应 UITextView？，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/51642331/