swift - 为什么我的收藏 View 单元格颜色选择不起作用

Question

我的单元格在 StoryBoard 上设置为蓝色，但即使我在用户选择单元格时更改单元格背景颜色，它们仍然是蓝色(不是红色)。我的代码有什么问题？

func collectionView(_ collectionView: UICollectionView, didSelectItemAt indexPath: IndexPath) {
    let cell = collectionView.dequeueReusableCell(withReuseIdentifier: "throneCell", for: indexPath) as! CharacterViewCell
    let character = characters[indexPath.row]
    cell.backgroundColor = UIColor.red
    onBoardingService.pickCharacter(character: character)
}

func collectionView(_ collectionView: UICollectionView, didDeselectItemAt indexPath: IndexPath) {
    let cell = collectionView.dequeueReusableCell(withReuseIdentifier: "throneCell", for: indexPath) as! CharacterViewCell
    let character = characters[indexPath.row]
    onBoardingService.removeCharacter(character: character)
}

Answer 1

替换

let cell = collectionView.dequeueReusableCell(withReuseIdentifier: "throneCell", for: indexPath) as! CharacterViewCell

与

let cell = collectionView.cellForItem(at: indexPath) as! CharacterViewCell

Don't use dequeueReusableCell out of cellForItemAt as it'll return a cell that's not the clicked one

didDeselectItemAt 可能会在单元格不在此处时被调用，

guard let cell = collectionView.cellForItem(at: indexPath) as? CharacterViewCell else { return }

---

 var selectedIndex = 0

  func collectionView(_ collectionView: UICollectionView, cellForItemAt indexPath: IndexPath) -> UICollectionViewCell {

    let cell = collectionView.dequeueReusableCell(withReuseIdentifier: "throneCell", for: indexPath) as! CharacterViewCell
    let character = characters[indexPath.row]

    if selectedIndex == indexPath.row {
         onBoardingService.pickCharacter(character: character)
         cell.backgroundColor =  UIColor.red 
    else {
          cell.backgroundColor = UIColor.clear
          onBoardingService.removeCharacter(character: character)
    }



func collectionView(_ collectionView: UICollectionView, didSelectItemAt indexPath: IndexPath) {

    selectedIndex = indexPath.row
    collectionView.reloadData()
}

---

删除此方法

func collectionView(_ collectionView: UICollectionView, didDeselectItemAt indexPath: IndexPath) {
    let cell = collectionView.dequeueReusableCell(withReuseIdentifier: "throneCell", for: indexPath) as! CharacterViewCell
    let character = characters[indexPath.row]
    onBoardingService.removeCharacter(character: character)
}

关于单项取消

func collectionView(_ collectionView: UICollectionView, didSelectItemAt indexPath: IndexPath) {  
    selectedIndex = selectedIndex == indexPath.row ? nil : indexPath.row 
    collectionView.reloadData()
}

并声明

var selectedIndex:Int?