在UICollectionView中删除一个单元格后刷新单元格布局

Question

我创建了一个动态调整单元格高度的UICollectionView。 我正在调整单元格的大小：

func collectionView(_ collectionView: UICollectionView, layout collectionViewLayout: UICollectionViewLayout, sizeForItemAt indexPath: IndexPath) -> CGSize {
let approximatedwidthoftextview = view.frame.width - 70
let size = CGSize(width: approximatedwidthoftextview, height: 1000)
let attributes = [NSAttributedStringKey.font: UIFont(name: "Avenir Next", size: 18)]
let estimatedFrame = NSString(string: allnotes[indexPath.row].note).boundingRect(with: size, options: .usesLineFragmentOrigin, attributes: attributes, context: nil)
return CGSize(width: view.frame.width, height: estimatedFrame.height + 38)

}

当我删除一个单元格时，剩余单元格的布局有点奇怪。内容被切断了。

奇怪的是，导航到先前的视图控制器然后返回到此控制器会修复单元布局并且单元格恢复正常。

知道这里有什么问题吗？

import UIKit

private let reuseIdentifier = "Cell"

class AddedNotesCollectionViewController: UICollectionViewController, 
UICollectionViewDelegateFlowLayout {

var allnotes = [notesarray]()


override func viewDidAppear(_ animated: Bool) {

    print(allnotes.count)

}
override func viewDidLoad() {
    super.viewDidLoad()

    view.backgroundColor = UIColor(red:0.15, green:0.20, blue:0.22, alpha:1.0)
    // Uncomment the following line to preserve selection between presentations
    // self.clearsSelectionOnViewWillAppear = false

    // Register cell classes
    self.collectionView!.register(AddedNotesCollectionViewCell.self, forCellWithReuseIdentifier: reuseIdentifier)

    // Do any additional setup after loading the view.
}

override func didReceiveMemoryWarning() {
    super.didReceiveMemoryWarning()
    // Dispose of any resources that can be recreated.
}





override func collectionView(_ collectionView: UICollectionView, numberOfItemsInSection section: Int) -> Int {
    // #warning Incomplete implementation, return the number of items
    return allnotes.count
}

override func collectionView(_ collectionView: UICollectionView, didSelectItemAt indexPath: IndexPath) {
    var tag = indexPath.row
    print(tag)

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

    // Configure the cell

    cell.deleteBtn.layer.setValue(indexPath.row, forKey: "index")
    cell.deleteBtn.addTarget(self, action: #selector(deleteUser(sender:)), for: UIControlEvents.touchUpInside)
    cell.backgroundColor = allnotes[indexPath.row].prioritycolor
    cell.textview.text = allnotes[indexPath.row].note

    // Remove the button from the first cell

    return cell
}
//deleting cell func

@objc func deleteUser(sender:UIButton) {
    let i : Int = (sender.layer.value(forKey: "index")) as! Int
    allnotes.remove(at: i)
    addedNotesArrayGlobal.addednotesarrays.remove(at: i)

    collectionView?.reloadData()



}

override func viewDidLayoutSubviews() {
    super.viewDidLayoutSubviews()
    collectionView?.collectionViewLayout.invalidateLayout()
}
func collectionView(_ collectionView: UICollectionView, layout collectionViewLayout: UICollectionViewLayout, sizeForItemAt indexPath: IndexPath) -> CGSize {
    let approximatedwidthoftextview = view.frame.width - 70
    let size = CGSize(width: approximatedwidthoftextview, height: 1000)
    let attributes = [NSAttributedStringKey.font: UIFont(name: "Avenir Next", size: 18)]
    let estimatedFrame = NSString(string: allnotes[indexPath.row].note).boundingRect(with: size, options: .usesLineFragmentOrigin, attributes: attributes, context: nil)
    return CGSize(width: view.frame.width, height: estimatedFrame.height + 32)
}

}

Answer 1

即使动态调整大小在使用上述算法的collectionView中运行良好，但它还不完整。我切换到UITableView并使用自动布局来进行动态调整大小。它简单，容易且工作得很好。