根据 CollectionView 中的选择更改 ImageView

Question

我目前有一个 CollectionView 和 1 个可重复使用的单元格，其中填满了 ImageView。这个单元格被使用了 10 次来展示 10 种不同的动物（我提供了单元格的图片）。我在这个集合视图上方也有一个标签。每次用户按下单元格时，标签都会变为“所选动物的名称”。 我现在想要的是让单元格图像在被选中时变暗，在未选中时恢复正常。到目前为止，我知道如何将单元格的图像更改为更暗的图像手动将其切换为较暗的，但我不知道如何将其更改为正常，因为我选择了另一个。 我该如何实现？我在底部复制了我的代码：

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

        //define the cell
        let cell = collectionview.dequeueReusableCell(withReuseIdentifier: "Cell", for: indexPath) as! AnimalSelectionCell

        //animals is name of array of different types of animals
        cell.animalImage.image = UIImage(named: animals[indexPath.row])
        cell.animalImage.restorationIdentifier = animals[indexPath.row]

        return cell
    }

    //choosing an animal
    func collectionView(_ collectionView: UICollectionView, didSelectItemAt indexPath: IndexPath) {        
            let currentCell = collectionview.cellForItem(at: indexPath) as! AnimalSelectionCell
            let animal = currentCell.animalImage.restorationIdentifier! //gets what type of animal selected
            selectionLabel.text = "\(animal) selected" //changes label
            currentCell.animalImage.image = UIImage(named: animal + "Selected") //changes to darker animal image                 
        }

Answer 1

您可以定义一个名为 selectedIndexpath 的 var 并在您的 didSelectItemAt 方法中通过选定的 indexpath 进行更改，如果 selectedIndexPath 相同，您应该将 selectedIndexpath 设置为 nil 并且在您的 cellForItemAt 方法中您只需要检查当前 indexPath 是否等于您的 selectedIndexpath 属性

var selectedIndexPath : IndexPath? //declare this

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

        //define the cell
        let cell = collectionview.dequeueReusableCell(withReuseIdentifier: "Cell", for: indexPath) as! AnimalSelectionCell

        //animals is name of array of different types of animals
        cell.animalImage.image = UIImage(named: animals[indexPath.row])
        if(indexPath == selectedIndexPath){
            //if indexpath is selected use your darker image
            cell.animalImage.image = UIImage(named: animal + "Selected")
        }
        cell.animalImage.restorationIdentifier = animals[indexPath.row]
        return cell
    }

    //choosing an animal
    func collectionView(_ collectionView: UICollectionView, didSelectItemAt indexPath: IndexPath) {        
            let currentCell = collectionview.cellForItem(at: indexPath) as! AnimalSelectionCell
            let animal = currentCell.animalImage.restorationIdentifier! //gets what type of animal selected
            selectionLabel.text = "\(animal) selected" //changes label
            var prevSelectedIndexPath : IndexPath?
            if(selectedIndexPath != nil){
                 if(selectedIndexPath == indexPath){
                     selectedIndexPath = nil
                 }else{
                     prevSelectedIndexPath = IndexPath(row: selectedIndexPath.row, section: selectedIndexPath.section)
                     selectedIndexPath = indexPath
                 }
            }else{
                selectedIndexPath = indexPath
            }

            if(prevSelectedIndexPath != nil){
                 collectionView.reloadItems(at: [indexPath,prevSelectedIndexPath])
            }else{
                 collectionView.reloadItems(at: [indexPath])
            }
        }

func clearSelection(){
    if(selectedIndexPath != nil){
         let prevSelectedIndexPath = IndexPath(row: selectedIndexPath.row, section: selectedIndexPath.section)
         selectedIndexPath = nil
         self.collectionView.reloadItems(at: [prevSelectedIndexPath])
    }
}

Answer 2

为此，您必须继承 UICollectionViewCell 并覆盖 isSelected 属性：

class MyCell: UICollectionViewCell {
    override var isSelected {
        willSet(bool) {
            self.backgroundColor = UIColor.gray // or whatever
        }
    }
}