使用 scrollViewDidScroll 处理多个 Collection View Cells

Posted 2023-02-23

【中文标题】使用 scrollViewDidScroll 处理多个 Collection View Cells

【英文标题】：Using scrollViewDidScroll to handle multiple Collection View Cells

【发布时间】：2021-03-15 23:05:43

【问题描述】：

我目前正在使用scrollViewDidScroll 为我的UICollectionView 单元格的偏移设置动画。集合视图以前只包含 1 个UICollectionViewCell。

我刚刚在同一个集合视图中添加了另一个UICollectionViewCell，并希望执行相同的动画。问题是，我遇到了错误：

Precondition failed: NSArray element failed to match the Swift Array Element type. Expected DetailedCell but found BasicCell

我的进步：

func scrollViewDidScroll(_ scrollView: UIScrollView) 
    // First (Detailed Cell)
    for newDetailedCell in mainCV.visibleCells as! [DetailedCell]  // Crashes on this line
        let indexPath = mainCV.indexPath(for: newDetailedCell)
        print("indexPath for Detailed Cell: \(indexPath)")
    

    // Rest (Basic Cell)
    for basic in mainCV.visibleCells as! [BasicCell] 
        let indexPath = mainCV.indexPath(for: basic)
        print("indexPath for Basic Cell: \(indexPath)")
    

如何使用两个不同的 CollectionViewCells 访问 visibleCells？

【参考方案1】：

你可以试试

for cell in mainCV.visibleCells 
   if let res = cell as? DetailedCell 
     //
   
   else 
   if let res = cell as? BasicCell 
     //
   
  

或

let detailCells  = mainCV.visibleCells.filter  $0 is DetailedCell   
for newDetailedCell in detailCells as! [DetailedCell]   
    let indexPath = mainCV.indexPath(for: newDetailedCell)
    print("indexPath for Detailed Cell: \(indexPath)")

【参考方案2】：

要处理多个UICollectionView 的滚动事件，请在scrollViewDidScroll 中实现此条件：

func scrollViewDidScroll(_ scrollView: UIScrollView) 
    
    if scrollView == collectionView1 
    
        // Your code goes here
        
    

    if scrollView == collectionView2 
    
        // Your code goes here