禁用 UICollectionView 的单向滑动

Question

我在一个单元格中有一个 collectionView。 collectionView 在水平方向滑动。

在collectionView中我调用了这个函数：

func scrollViewDidScroll(_ scrollView: UIScrollView) {
    let offset = scrollView.contentOffset.x
    print(offset)
}

当偏移量为 0 时，用户无需向左滑动，因为在该方向上看不到任何东西。

当偏移量为 0 时，如何暂时禁用单向滚动？在这种情况下，在向右滚动时禁用向左滚动仍然处于启用状态。

编辑：我忘了说，带有 collectionView 的单元格位于 collectionView 的另一个单元格内，这两个单元格都水平滚动。我想在子单元格上禁用滚动并同时在父单元格上启用滚动。所以，当子单元格内的collectionView水平滚动不再启用时，父单元格开始滚动。

class ViewController: UIViewController {

lazy var collectionView : UICollectionView = {
    let layout = UICollectionViewFlowLayout()
    layout.scrollDirection = .horizontal
    let cv = UICollectionView(frame: .zero, collectionViewLayout: layout)
    cv.delegate = self
    cv.dataSource = self
    cv.isPagingEnabled = true
    return cv
}()

    func collectionView(_ collectionView: UICollectionView, cellForItemAt indexPath: IndexPath) -> UICollectionViewCell {
    if indexPath.item == 0 {
                    // Other cell here to swipe to when user cant swipe collectionView inside child cell.
    } else {
        let cell = collectionView.dequeueReusableCell(withReuseIdentifier: ParentCell.reuseIdentifier, for: indexPath) as! ParentCell
        return cell
    }
}

}

父单元：

class ParentCell: UICollectionViewCell {

lazy var collectionView : UICollectionView = {
    let layout = UICollectionViewFlowLayout()
    layout.scrollDirection = .vertical
    let cv = UICollectionView(frame: .zero, collectionViewLayout: layout)
    cv.delegate = self
    cv.dataSource = self
    cv.isPagingEnabled = true
    cv.showsHorizontalScrollIndicator = false
    return cv
}()


func collectionView(_ collectionView: UICollectionView, cellForItemAt indexPath: IndexPath) -> UICollectionViewCell {

    let cell = collectionView.dequeueReusableCell(withReuseIdentifier: ChildCell.reuseIdentifier, for: indexPath) as! ChildCell
    return cell

}

func collectionView(_ collectionView: UICollectionView, layout collectionViewLayout: UICollectionViewLayout, sizeForItemAt indexPath: IndexPath) -> CGSize {
    return CGSize(width: view.frame.width, height: view.frame.height)
}


}

子细胞：

class ChildCell: UICollectionViewCell {

lazy var collectionView : UICollectionView = {
    let layout = UICollectionViewFlowLayout()
    layout.scrollDirection = .horizontal
    let cv = UICollectionView(frame: .zero, collectionViewLayout: layout)
    cv.delegate = self
    cv.dataSource = self
    cv.tag = 1
    return cv
}()


func scrollViewDidScroll(_ scrollView: UIScrollView) {
    let offset = scrollView.contentOffset.x
    print(offset)
}
}

Answer 1

您可以使用以下命令强制偏移：

func scrollViewDidScroll(_ scrollView: UIScrollView) {
    if scrollView == myNotScrollingView {
        //you will never bounce to left
        scrollView.contentOffset.x = max(0,scrollView.contentOffset.x)
    }
}

Answer 2

喜欢

 // create one global float value for get the every scroll
 var previousX: Float = 0.0

为你的父子collectionview设置tag，然后根据tag访问

func scrollViewDidScroll(_ scrollView: UIScrollView) {

if scrollView.contentOffset.x < previousX {
      if  scrollView.tag == 1 // set your tag
    {
    scrollView.contentOffset = CGPoint(x: CGFloat(previousX), y: CGFloat(scrollView.contentOffset.y))
}
else {
    previousX = scrollView.contentOffset.x
}
    }
}

更新

   func scrollViewDidScroll(_ scrollView: UIScrollView) {

 if scrollView.contentOffset.x < previousX {

      var cell: UICollectionViewCell? = (UICollectionView.viewwithtag(1) as? UICollectionViewCell)



      if  cell.tag == 1 // set your tag
    {
    scrollView.contentOffset = CGPoint(x: CGFloat(previousX), y: CGFloat(scrollView.contentOffset.y))
}
else {
    previousX = scrollView.contentOffset.x
}
    }
}

更新 2

   func scrollViewDidScroll(_ scrollView: UIScrollView) {

 if scrollView.contentOffset.x < previousX {

      var cell: UICollectionViewCell? = (UICollectionView.viewwithtag(1) as? UICollectionViewCell)



      if (cell is ChildCell)
    {
    scrollView.contentOffset = CGPoint(x: CGFloat(previousX), y: CGFloat(scrollView.contentOffset.y))
}
else {
    previousX = scrollView.contentOffset.x
}
    }
}
else if (cell is ParentCell) {
//Another custom cell
 }
 else {
//General cell
}

}