如何调整 UICollectionView 单元格的大小以适合其中的内容？

Posted 2023-03-14

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【中文标题】如何调整 UICollectionView 单元格的大小以适合其中的内容？【英文标题】：How to size a UICollectionView cell to fit the contents inside it? 【发布时间】：2017-01-08 20:06:24 【问题描述】：

我正在考虑在sizeForItemAt 中执行此操作，但我无法访问那里的单元格内容的高度。尝试在cellForItemAt 中执行此操作，因为我们正在那里创建单元格的实例，并且可以在那里引用它的所有内容及其高度，但是在此方法中设置单元格的帧大小似乎不起作用。似乎只能在sizeForItemAt 中正确设置大小。这是我尝试在cellForItemAt 中执行此操作的示例（请注意，在此方法中，我添加了likesCommentsLabel 视图，具体取决于它是否具有为其.text 分配的字符串，这就是使高度动态的原因）：

    override func collectionView(_ collectionView: UICollectionView, cellForItemAt indexPath: IndexPath) -> UICollectionViewCell 
    let feedCell = collectionView.dequeueReusableCell(withReuseIdentifier: cellId, for: indexPath) as! FeedCell

    feedCell.post = posts[indexPath.item] //This executes post setter and didSet in FeedCell class

    //Determine whether to add likesCommentsLabel
    if (feedCell.likesCommentsLabel.text != nil) 
        feedCell.addSubview(feedCell.likesCommentsLabel)
        feedCell.addConstraintsWithFormat(format: "H:|-12-[v0]|", views: feedCell.likesCommentsLabel)
        feedCell.addConstraintsWithFormat(format: "V:|-8-[v0(44)]-4-[v1]-4-[v2(200)]-8-[v3(24)]-8-[v4(0.4)][v5(44)]|", views: feedCell.profileImageView, feedCell.statusTextView, feedCell.statusImageView, feedCell.likesCommentsLabel, feedCell.dividerLineView, feedCell.credibilityButton)

        print("THIS RUNS")
    
    else 
        feedCell.addConstraintsWithFormat(format: "V:|-8-[v0(44)]-4-[v1]-4-[v2(200)]-8-[v3(0.4)][v4(44)]|", views: feedCell.profileImageView, feedCell.statusTextView, feedCell.statusImageView, feedCell.dividerLineView, feedCell.credibilityButton)
        print("THIS RUNS MORE")
    

    //Determine size of cell based on status text  length
    if let statusText = posts[indexPath.item].statusText 
        let rect = NSString(string: statusText).boundingRect(with: CGSize(width: view.frame.width, height: 500), options: NSStringDrawingOptions.usesFontLeading.union(NSStringDrawingOptions.usesLineFragmentOrigin), attributes: [NSFontAttributeName: UIFont.systemFont(ofSize: 14)], context: nil)

        var knownHeight: CGFloat = 8.0 + 44.0 + 4.0 + 4.0 + 200.0 + 8.0 + 44.0

        //Add to height of cell, if there's a likes/comments label
        if (feedCell.likesCommentsLabel.text != nil) 
            knownHeight = CGFloat(8.0 + 44.0 + 4.0 + 4.0 + 200.0 + 8.0 + 24.0 + 8.0 + 44.0)
        
        else 
            knownHeight = CGFloat(8.0 + 44.0 + 4.0 + 4.0 + 200.0 + 8.0 + 44.0)
        
        //Calculate y position based off of previous cell. If no previous cell, y = 0.
        if indexPath.item > 0 
            feedCell.frame = CGRect(x: 0, y: ((collectionView.cellForItem(at: collectionView.indexPathsForVisibleItems[indexPath.item - 1])?.frame.origin.y)! +  (collectionView.cellForItem(at: collectionView.indexPathsForVisibleItems[indexPath.item - 1])?.frame.height)!), width: view.frame.width, height: rect.height + knownHeight + 20)
        
        else 
            feedCell.frame = CGRect(x: 0, y: 0, width: view.frame.width, height: rect.height + knownHeight + 20)
        
        print(feedCell.frame)
    

    return feedCell

【问题讨论】：

这实际上可能对您有所帮助：corsarus.com/2015/collection-view-with-self-sizing-cells 【参考方案1】：

覆盖 'viewDidLayoutSubviews' 方法并使您的 collectionview 的布局无效，例如，

 - (void)viewDidLayoutSubviews 
     [super viewDidLayoutSubviews];
  [yourCollectionView.collectionViewLayout invalidateLayout];