Question

我有30个项目的集合视图，并希望在出版时执行某些操作。我是这样做的：

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

    let cell = collectionView.cellForItemAtIndexPath(indexPath) as! ItemCell

    var translucentView = ILTranslucentView(frame: CGRectMake(0, 0, cell.contentView.frame.size.width, cell.contentView.frame.size.height))
    translucentView.translucentAlpha = 0.9
    translucentView.translucentStyle = UIBarStyle.BlackTranslucent
    translucentView.translucentTintColor = UIColor.clearColor()
    translucentView.backgroundColor = UIColor.clearColor()
    translucentView.alpha = 0.0
    cell.contentView.addSubview(translucentView)
    UIView.animateWithDuration(0.4, animations: {
        translucentView.alpha = 1.0
    })
}

该功能按预期工作，但视图不仅出现在分接的单元格上，而且出现在屏幕上不可见的相同位置的单元格上。因此，如果屏幕上有3个可见单元格并点击数字1，那么当我滚动时，视图已被添加到单元格4,7等...

Answer 1

UICollectionView重复使用UITableView之类的单元格。当一个单元格在屏幕外滚动时，它将被添加到队列中，并将被重新用于下一个要在屏幕上滚动的单元格（例如单元格4,7 ...）。

只需删除translucentView即可解决此问题：

UIView.animateWithDuration(0.4, animations: { () -> Void in
    translucentView.alpha = 1.0
}) { (finish) -> Void in
    translucentView.removeFromSuperview()
}

您可以在translucentView中创建ItemCell并使用cellForItemAtIndexPath方法更新其状态：

override func collectionView(collectionView: UICollectionView, cellForItemAtIndexPath indexPath: NSIndexPath) -> UICollectionViewCell {
    let cell = collectionView.dequeueReusableCellWithReuseIdentifier(CellIdentifier, forIndexPath: indexPath) as! ItemCell

    if find(collectionView.indexPathsForSelectedItems() as! [NSIndexPath], indexPath) != nil {
        cell.translucentView.alpha = 1.0
    } else {
        cell.translucentView.alpha = 0.0
    }

    return cell
}

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

    let cell = collectionView.cellForItemAtIndexPath(indexPath) as! ItemCell

    UIView.animateWithDuration(0.4, animations: {
        cell.translucentView.alpha = 1.0
    })
}

override func collectionView(collectionView: UICollectionView, didDeselectItemAtIndexPath indexPath: NSIndexPath) {
    let cell = collectionView.cellForItemAtIndexPath(indexPath) as! ItemCell

    UIView.animateWithDuration(0.4, animations: {
        cell.translucentView.alpha = 0.0
    })
}

Answer 2

您是否正确设置了numberOfSectionsInTableView？

 func numberOfSectionsInCollectionView(collectionView: UICollectionView) -> Int      {
    return 1
}

didSelectItemAtIndexPath修改UICollectionView中的多个单元格

2 个答案: