Question

我有一个带水平滚动方向和启用分页的collectionView，现在我想让它像AppStore上的游戏部分一样顺畅滚动。

更具体地说，这就是我想要的第一个单元格：

修改

我实际上实现了两个宽度较小的下一个图像在selectItem中使用.centeredHorizontally的单元格和下一个单元格，我的问题是不顺畅滚动。

正如你所看到的那样，第二个细胞正在出现。

以下是下一个细胞：

正如您现在所看到的那样，上一个和下一个单元格正在出现。

我设法通过设置这部分代码来做到这一点，但是作为AppStore没有顺利弹跳。

这是我使用的代码：

       func scrollViewDidEndDecelerating(_ scrollView: UIScrollView) {
            var visibleRect = CGRect()

            visibleRect.origin = collectionView.contentOffset
            visibleRect.size = collectionView.bounds.size

            let visiblePoint = CGPoint(x: visibleRect.midX, y: visibleRect.midY)

            let visibleIndexPath: IndexPath = collectionView.indexPathForItem(at: visiblePoint) ?? IndexPath()
            let indexPath = IndexPath(item: visibleIndexPath[1], section: 0)
            collectionView.selectItem(at: indexPath, animated: true, scrollPosition: .centeredHorizontally )

        }

这是我的collectionView代码：

func collectionView(_ collectionView: UICollectionView, layout collectionViewLayout: UICollectionViewLayout, minimumInteritemSpacingForSectionAt section: Int) -> CGFloat {
        return 0
    }

    func collectionView(_ collectionView: UICollectionView, layout collectionViewLayout: UICollectionViewLayout, minimumLineSpacingForSectionAt section: Int) -> CGFloat {
        return 0
    }

    func collectionView(_ collectionView: UICollectionView, layout collectionViewLayout: UICollectionViewLayout, sizeForItemAt indexPath: IndexPath) -> CGSize {

        let frameSize = collectionView.frame.size
        return CGSize(width: frameSize.width - 30, height: frameSize.height - 40)
    }

    func collectionView(_ collectionView: UICollectionView, layout collectionViewLayout: UICollectionViewLayout, insetForSectionAt section: Int) -> UIEdgeInsets {
        return UIEdgeInsets(top: 0, left: 0, bottom: 20, right: 0)
    }

Answer 1

Example project here

在课堂上属性

     var itemSize = CGSize(width: 0, height: 0)
     @IBOutlet weak var collectionViewHeight: NSLayoutConstraint!
     @IBOutlet weak var collectionView: UICollectionView!
     fileprivate let sectionInsets = UIEdgeInsets(top: 0, left: 0, bottom: 0, right: 0)

在viewDidLoad或awakeFormNib中（如果在collectionViewCell或tableViewCell中）

    if let layout = collectionView.collectionViewLayout as? UICollectionViewFlowLayout {
        layout.minimumLineSpacing = 0
        layout.minimumInteritemSpacing = 0
    }
    collectionView.contentInset = UIEdgeInsets(top: 0, left: 16, bottom: 0, right: 8)
    collectionView.isPagingEnabled = false
    layoutIfNeeded()

    let width = collectionView.bounds.size.width-24
    let height = width * (3/4)
    itemSize = CGSize(width: width, height: height)
    layoutIfNeeded()

实施UICollectionViewDelegateFlowLayout

    func collectionView(_ collectionView: UICollectionView,
                    layout collectionViewLayout: UICollectionViewLayout,
                    insetForSectionAt section: Int) -> UIEdgeInsets {

        return sectionInsets
    }

    func collectionView(_ collectionView: UICollectionView,
                    layout collectionViewLayout: UICollectionViewLayout,
                    sizeForItemAt indexPath: IndexPath) -> CGSize {
        return itemSize
    }

实施ScrollViewDelegate

func scrollViewWillEndDragging(_ scrollView: UIScrollView, withVelocity velocity: CGPoint, targetContentOffset: UnsafeMutablePointer<CGPoint>) {
    let pageWidth = itemSize.width
    targetContentOffset.pointee = scrollView.contentOffset
    var factor: CGFloat = 0.5
    if velocity.x < 0 {
        factor = -factor
        print("right")
    } else {
        print("left")
    }

    let a:CGFloat = scrollView.contentOffset.x/pageWidth
    var index = Int( round(a+factor) )
    if index < 0 {
        index = 0
    }
    if index > collectionViewDataList.count-1 {
        index = collectionViewDataList.count-1
    }
    let indexPath = IndexPath(row: index, section: 0)
    collectionView?.scrollToItem(at: indexPath, at: .left, animated: true)
}

请参阅我的项目在过去的游乐设施部分的示例屏幕截图我在collectionViewCell中实现了uicollectionview

Answer 2

设置collectionView?.isPagingEnabled = true并移除您的scrollViewDidEndDecelerating方法

使collectionView滚动为AppStore游戏部分

2 个答案: