更新CollectionView未選中的單元格？

Question

我有一個CollectionView，允許用戶觸摸一個單元格，它會更改邊框顏色。但是，我一次只想選擇一個單元格。如何編輯此代碼，以便使用邊框顏色更新indexpath處的單元格，並且之前選定的單元格將被重置？

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 

謝謝！

UPDATE

 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

你爲什麼不有一個實例變量（在類文件的開頭添加）每次都存先前選定的單元格

var previouslySelectedIndexPath: NSIndexPath? 

然後一個新的小區被選中時，首先刪除先前選定單元格的邊框，然後將邊框添加到新選單元格

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

您可以實現

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

下面是一個使用香草UICollectionViewCell一個例子：

// 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 
    } 
}