Question

我有一个CollectionView，允许用户触摸单元格，它将改变边框颜色。但是，我只希望一次选择一个单元格。如何编辑此代码，以便使用边框颜色更新indexpath处的单元格并重置先前选定的单元格？

 override func collectionView(collectionView: UICollectionView, didSelectItemAtIndexPath indexPath: NSIndexPath) {

        self.user["avatar"] = self.avatars[indexPath.row]

        do {
           try self.user.save()
        } catch {
            print(error)
        }

        let cell = collectionView.cellForItemAtIndexPath(indexPath) as! AvatarViewCell
        cell.layer.borderWidth = 5.0
        cell.layer.borderColor = UIColor.purpleColor().CGColor

谢谢！

更新

       let cell = collectionView.cellForItemAtIndexPath(indexPath) as! AvatarViewCell
        var previouslySelectedIndexPath: NSIndexPath?
        if previouslySelectedIndexPath != nil {
            let previousCell = collectionView.cellForItemAtIndexPath(previouslySelectedIndexPath!) as! AvatarViewCell
            previousCell.layer.borderWidth = 0
            previousCell.layer.borderColor = UIColor.whiteColor().CGColor
        }

        cell.layer.borderWidth = 5.0
        cell.layer.borderColor = UIColor.purpleColor().CGColor

Answer 1

为什么没有实例变量（在类文件的开头添加）来存储先前选择的单元格

var previouslySelectedIndexPath: NSIndexPath?

然后，每次选择新单元格时，首先从先前选定的单元格中删除边框，然后将边框添加到新选择的单元格

if previouslySelectedIndexPath != nil {
    let previousCell = collectionView.cellForItemAtIndexPath(previouslySelectedIndexPath!) as! AvatarViewCell
    previousCell.borderWidth = 0
}
let currentCell = collectionView.cellForItemAtIndexPath(indexPath) as! AvatarViewCell
cell.layer.borderWidth = 5.0
cell.layer.borderColor = UIColor.purpleColor().CGColor
previouslySelectedIndexPath = indexPath

Answer 2

您可以实施

func collectionView(collectionView: UICollectionView, didDeselectItemAtIndexPath indexPath: NSIndexPath)

以下是使用vanilla UICollectionViewCell的示例：

// MARK: UICollectionViewDelegate

override func collectionView(collectionView: UICollectionView, didSelectItemAtIndexPath indexPath: NSIndexPath) {

    if let cell = collectionView.cellForItemAtIndexPath(indexPath) {
        cell.layer.borderWidth = 5.0
        cell.layer.borderColor = UIColor.purpleColor().CGColor
    }
}

override func collectionView(collectionView: UICollectionView, didDeselectItemAtIndexPath indexPath: NSIndexPath) {

    if let cell = collectionView.cellForItemAtIndexPath(indexPath) {
        cell.layer.borderWidth = 0
        cell.layer.borderColor = UIColor.whiteColor().CGColor
    }
}

更新未选中的CollectionView单元格？

2 个答案: