ios - UICollectionViewCell 中的动态高度 noScrollable UICollectionView

Question

我想将动态高度 nonScrollable UICollectionView添加到UICollectionViewCell中。 (按照 Ash Furrow 的解释，在 UICollectionViewCell 中添加静态高度 UICollectionView 很容易)

花了几个小时在网上搜索后，我仍然不明白。

这就是我想要的

我们打电话吧:主要CollectionView:ParentCollectionView
CollectionView 内部:ChildCollectionView

我想获取 ChildCollectionView 的高度，以便我可以在侧面设置 ParentCollectionView 的单元格大小:

func collectionView(_ collectionView: UICollectionView, layout collectionViewLayout: UICollectionViewLayout, sizeForItemAt indexPath: IndexPath) -> CGSize {
        let text = "I'm trying to get a label in a cell.."
        let options = NSStringDrawingOptions.usesFontLeading.union(.usesLineFragmentOrigin)
        let estimatedFrameForEventText = (text as NSString).boundingRect(with: CGSize.init(width: view.frame.width - 30, height: 1000), options: options, attributes: [NSFontAttributeName: UIFont.systemFont(ofSize: 12)], context: nil)
        return CGSize.init(width: view.frame.width - 10, height: 320 + estimatedFrameForEventText.height + 60)
}

还想用以下方法更改 ChildCollectionView 的高度常量:

override func collectionView(_ collectionView: UICollectionView, cellForItemAt indexPath: IndexPath) -> UICollectionViewCell {
        let cell = collectionView.dequeueReusableCell(withReuseIdentifier: eventCellId, for: indexPath) as! EventCell
        cell.eventText.text = "I'm trying to get a label in a cell.."

        // height constraint of ChildCollectionView in ParentCell
        cell.collectionViewHeightConstraint.constant = cell.collectionView.intrinsicContentSize.height
        return cell
}

故意禁用 ChildCollectionView 的滚动，以将 ChildCollectionViewCell 全部显示在一起。

这就是我被困的地方

我无法预先计算 ChildCollectionView 以将它们传递给 ParentCollectionView 委托(delegate)

两个 CollectionView 都使用 UICollectionViewFlowLayout

我是 iOS 开发新手。任何帮助将不胜感激:)

Answer 1

这解决了我的问题

ParentCollectionViewController

var height: CGFloat!

override func collectionView(_ collectionView: UICollectionView, cellForItemAt indexPath: IndexPath) -> UICollectionViewCell {
    let cell = collectionView.dequeueReusableCell(withReuseIdentifier: eventCellId, for: indexPath) as! EventCell

    cell.collectionViewHeightConstraint.constant = height!
    return cell
}

func collectionView(_ collectionView: UICollectionView, layout collectionViewLayout: UICollectionViewLayout, sizeForItemAt indexPath: IndexPath) -> CGSize {
    let options = NSStringDrawingOptions.usesFontLeading.union(.usesLineFragmentOrigin)
    var sizeOfChildCell: CGRect!
    var widthOfCells: CGFloat! = 0.0
    let cellPadding = 10
    let widthOfChildCollectionview = view.frame.width - 120
    for tag in tags {
        sizeOfChildCell = ("#\(tag)" as NSString).boundingRect(with: CGSize.init(width: widthOfChildCollectionview, height: 1000), options: options, attributes: [NSFontAttributeName: UIFont.systemFont(ofSize: 12)], context: nil)
        widthOfCells = widthOfCells + sizeOfChildCell.width + cellPadding + 3.8
    }
    let numOfRows = ceil(widthOfCells / widthOfChildCollectionview)
    height = numOfRows  * 25
    height = height + numOfRows * 3.8
    return CGSize.init(width: view.frame.width - 10, height: 320  + height)
}

ParentCollectionViewCell

var childCollectionViewHeightConstraint: NSLayoutConstraint!

lazy var childCollectionView: UICollectionView = {
    let layout = UICollectionViewFlowLayout()
    let cv = UICollectionView(frame: .zero, collectionViewLayout: layout)
    cv.showsVerticalScrollIndicator = false
    cv.isScrollEnabled = false
    cv.contentInset = UIEdgeInsetsMake(0, 0, 0, 0)
    cv.backgroundColor = .white
    cv.dataSource = self
    cv.delegate = self
    return cv
}()

 override init(frame: CGRect) {
    super.init(frame: frame)

    childCollectionViewHeightConstraint = NSLayoutConstraint(item: childCollectionView, attribute: .height, relatedBy: .equal, toItem: nil, attribute: .notAnAttribute, multiplier: 1.0, constant: 96)
    addConstraint(childCollectionViewHeightConstraint)

}