单元格中的UICollectionview视图绘图不正确

Question

我正在为Apple-tv编写一个聊天应用程序，我有一个在细胞聊天中显示自定义视图的问题。

我有代码：

func collectionView(collectionView: UICollectionView, cellForItemAtIndexPath indexPath: NSIndexPath) ->
        UICollectionViewCell {
            var myCell = self.chatCollectionView.dequeueReusableCellWithReuseIdentifier(chatCellIdentifier, forIndexPath: indexPath) as UICollectionViewCell
            myCell.removeFromSuperview()
                currentIndexPath = indexPath
                if flag[indexPath.row]==0
                {
                myCell = sendBotMessage(historyString[indexPath.row], path: indexPath, collectionView: chatCollectionView)
                }
                else
                {
                myCell = sendUserMessage(historyString[indexPath.row], path: indexPath, collectionView: chatCollectionView)
                }
            return myCell
    }

代码显示两个版本的消息，如图所示，sendBotMessage和sendUserMessage。问题是前一个单元格的显示不正确。第一次使用1个sendBotMessage-view运行

在添加第二项之后

第二条(右)由sendUserMessage添加的消息，另一个视图。“对应关系”的整个历史都存储在historyString中--一个string类型的数组。当滚动显示错误消失时，存储被正确组织。因此，可以得出渲染函数的正确性的结论。

在调用reloadData()和collectionView之后，在historyString中附加的所有新消息都必须重新绘制。

我可能会犯错的地方？我试图清理collectionView的subview，禁用滚动动画，但没有帮助。

程序绘图视图的代码：

    func sendUserMessage(text : String, path : NSIndexPath, collectionView : UICollectionView) -> UICollectionViewCell {

        let userMessage = text
        let textSize = getTextFrameSize(userMessage)
        let frameForMessage = getFrameforView(textSize) 

        let messageBuble = Chat_ViewInCell(frame: frameForMessage, textSize: textSize, text: userMessage)
        messageBuble.backgroundColor = UIColor.clearColor()

        let avatarImage = UIImage(named: "\(userAvatar+1).png")
        let avatarView = UIImageView(image: avatarImage)
        avatarView.contentMode = UIViewContentMode.ScaleAspectFit

        let totalX = messageBuble.frame.width + 340
        let constraint = 1750 - totalX
        messageBuble.frame.origin = CGPointMake(constraint, 0)
        avatarView.frame = CGRectMake(messageBuble.frame.maxX + 10, 0, 170, 170)

        let cell = collectionView.dequeueReusableCellWithReuseIdentifier(chatCellIdentifier, forIndexPath: path) as! chatCollectionViewCell
        //добавляем, счастье, радуемся
        cell.addSubview(messageBuble)
        cell.addSubview(avatarView)
        return cell
    }
func sendBotMessage(text : String, path : NSIndexPath, collectionView : UICollectionView) -> UICollectionViewCell {

        let userMessage = text
        let textSize = getTextFrameSize(userMessage)
        let frameForMessage = getFrameforView(textSize) 

        let messageBuble = bot_ViewInCell(frame: frameForMessage, textSize: textSize, text: userMessage)
        messageBuble.backgroundColor = UIColor.clearColor()

        let avatarImage = UIImage(named: partner_image)
        let avatarView = UIImageView(image: avatarImage)
        avatarView.contentMode = UIViewContentMode.ScaleAspectFit
        avatarView.frame = CGRectMake(0, 0, 170, 170)
        let constraint = avatarView.frame.maxX + 10
        messageBuble.frame.origin = CGPointMake(constraint, 0)

        let cell = collectionView.dequeueReusableCellWithReuseIdentifier(chatCellIdentifier, forIndexPath: path) as! chatCollectionViewCell
        //добавляем в возвращаемую ячейку
        cell.addSubview(avatarView)
        cell.addSubview(messageBuble)
        return cell
    }

在推荐使用自定义CollectionCellView进行更改后，我得到了以下代码：

func collectionView(collectionView: UICollectionView, cellForItemAtIndexPath indexPath: NSIndexPath) ->
    UICollectionViewCell {
        var myCell = chatCollectionView.dequeueReusableCellWithReuseIdentifier(chatCellIdentifier, forIndexPath: indexPath) as! chatCollectionViewCell
        var customCell = myCell
            if flag[indexPath.row]==0
            {
            customCell = sendBotMessage(historyString[indexPath.row], path: indexPath, collectionView: collectionView)
            }
            else
            {
            customCell = sendUserMessage(historyString[indexPath.row], path: indexPath, collectionView: collectionView)
            }
        myCell = customCell
        currentIndexPath = indexPath
        return myCell
}

函数对自定义单元格也有更改：

    func sendUserMessage(text : String, path : NSIndexPath, collectionView : UICollectionView) -> chatCollectionViewCell {

    let userMessage = text
    let textSize = getTextFrameSize(userMessage) //высчитали необходимые размеры лейбла
    let frameForMessage = getFrameforView(textSize) //высчиитали необходимые размеры всей вьюшки

    let messageBuble = Chat_ViewInCell(frame: frameForMessage, textSize: textSize, text: userMessage)
    messageBuble.backgroundColor = UIColor.clearColor()

    //создаем аватар
    let avatarImage = UIImage(named: "\(userAvatar+1).png")
    let avatarView = UIImageView(image: avatarImage)
    avatarView.contentMode = UIViewContentMode.ScaleAspectFit

    //считаем отступ до правого края, позицию аватара
    let totalX = messageBuble.frame.width + 340
    let constraint = 1750 - totalX
    messageBuble.frame.origin = CGPointMake(constraint, 0)
    avatarView.frame = CGRectMake(messageBuble.frame.maxX + 10, 0, 170, 170)

    let cell = collectionView.dequeueReusableCellWithReuseIdentifier(chatCellIdentifier, forIndexPath: path) as! chatCollectionViewCell
    //добавляем, счастье, радуемся
    cell.addSubview(messageBuble)
    cell.addSubview(avatarView)
    return cell
}

    func sendBotMessage(text : String, path : NSIndexPath, collectionView : UICollectionView) -> chatCollectionViewCell {

    let userMessage = text
    let textSize = getTextFrameSize(userMessage) //высчитали необходимые размеры лейбла
    let frameForMessage = getFrameforView(textSize) //высчиитали необходимые размеры всей вьюшки

    //создали всю вьюшку
    let messageBuble = bot_ViewInCell(frame: frameForMessage, textSize: textSize, text: userMessage)
    messageBuble.backgroundColor = UIColor.clearColor()

    //создаем аватар и считаем его позицию
    let avatarImage = UIImage(named: partner_image)
    let avatarView = UIImageView(image: avatarImage)
    avatarView.contentMode = UIViewContentMode.ScaleAspectFit
    avatarView.frame = CGRectMake(0, 0, 170, 170)
    let constraint = avatarView.frame.maxX + 10
    messageBuble.frame.origin = CGPointMake(constraint, 0)

    let cell = collectionView.dequeueReusableCellWithReuseIdentifier(chatCellIdentifier, forIndexPath: path) as! chatCollectionViewCell
    //добавляем в возвращаемую ячейку
    cell.addSubview(avatarView)
    cell.addSubview(messageBuble)
    return cell
}

但是问题没有解决。我在自定义CollectionViewCell中做错了什么？我必须做另一件事吗？

Answer 1

问题已经解决了！我不知道prepareForReuse()方法。非常简单，在自定义单元格类defeniton中，我必须覆盖它的方法，并调用子视图clearsContextBeforeDrawing和removeFromSuperview。代码如下：

class chatCollectionViewCell: UICollectionViewCell {

@IBOutlet weak var view: Chat_ViewInCell!

override func prepareForReuse() {
    super.prepareForReuse()
    for currView in self.subviews
    {
        currView.clearsContextBeforeDrawing = true
        currView.removeFromSuperview()
    }
}

一切正常，没有错误的重绘。