didSelectItemAtIndexPath修改UICollectionView中的多個單元格

Question

我有30個項目的收藏視圖，並希望在印刷時執行某些操作。 我這樣做：

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
    })
}

該功能將按預期工作，但是視圖不僅會出現在所單擊的單元格上，還會出現在屏幕上不可見的相同位置的單元格上。 因此，如果屏幕上有3個可見的單元格，而我點擊數字1，那么當我滾動查看時，該視圖已添加到單元格4、7等。

Answer 1

UICollectionView重用像UITableView這樣的單元格。 當一個單元在屏幕外滾動時，它被添加到隊列中，並將被重新用於下一個要在屏幕上滾動的單元（例如，單元4、7 ...）。

只需刪除translucentView解決此問題：

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

您可以在ItemCell創建translucentView並在cellForItemAtIndexPath方法中更新其狀態：

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

像這樣正確設置了numberOfSectionsInTableView嗎？

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