ios - iOS:在Swift3的collectionView中，当我向下滚动时，collectionView会自动位于顶部。如何停止呢？

我想让我的收藏视图停在牢房里。问题是当我向下滚动时，如果我松开它，它会自动出现在第一个位置。。。
我尝试了collection.alwaysBounceVertical=true但没有成功。。。
这是我的代码：

override func viewDidLoad() {
        super.viewDidLoad()

        let layout = OrganiserLayout()
        let frameCollection = CGRect(x: self.view.frame.origin.x, y: self.view.frame.origin.y, width: self.view.frame.width, height: self.view.frame.height + 1000)

        let collection = UICollectionView(frame: frameCollection, collectionViewLayout: layout)
        collection.delegate = self
        collection.dataSource = self
        collection.backgroundColor = UIColor.white
        collection.register(OrganiserCollectionViewCell.self, forCellWithReuseIdentifier: "cell")
        self.view.addSubview(collection)
        collection.alwaysBounceVertical = true
        collection.alwaysBounceHorizontal = true
        collection.bounces = true
        collection.isPagingEnabled = false
        collection.isScrollEnabled = true
}
    func numberOfSections(in collectionView: UICollectionView) -> Int {
        return 15
    }

        func collectionView(_ collectionView: UICollectionView, numberOfItemsInSection section: Int) -> Int {
            switch section {
            case 0:
                return 40
        }
    }

class OrganiserLayout:UICollectionViewLayout {

    let cellWidth:CGFloat = 100
    var attrDict = Dictionary<IndexPath,UICollectionViewLayoutAttributes>()
    var contentSize = CGSize.zero

    override var collectionViewContentSize : CGSize {
        return self.contentSize
    }

    override func prepare() {
        // Generate the attributes for each cell based on the size of the collection view and our chosen cell width
        if let cv = collectionView {
            let collectionViewHeight = cv.frame.height
            let numberOfSections = cv.numberOfSections
            self.contentSize = cv.frame.size
            self.contentSize.width = cellWidth*CGFloat(numberOfSections)
            for section in 0...numberOfSections-1 {
                let numberOfItemsInSection = cv.numberOfItems(inSection: section)
                let itemHeight = collectionViewHeight/CGFloat(numberOfItemsInSection)
                let itemXPos = cellWidth*CGFloat(section)
                for item in 0...numberOfItemsInSection-1 {
                    let indexPath = IndexPath(item: item, section: section)
                    let itemYPos = itemHeight*CGFloat(item)
                    let attr = UICollectionViewLayoutAttributes(forCellWith: indexPath)
                    attr.frame = CGRect(x: itemXPos, y: itemYPos, width: cellWidth, height: itemHeight)
                    attrDict[indexPath] = attr
                }
            }
        }
    }

    override func layoutAttributesForElements(in rect: CGRect) -> [UICollectionViewLayoutAttributes]? {
        // Here we return the layout attributes for cells in the current rectangle
        var attributesInRect = [UICollectionViewLayoutAttributes]()
        for cellAttributes in attrDict.values {
            if rect.intersects(cellAttributes.frame) {
                attributesInRect.append(cellAttributes)
            }
        }
        return attributesInRect
    }

    override func layoutAttributesForItem(at indexPath: IndexPath) -> UICollectionViewLayoutAttributes? {
        // Here we return one attribute object for the specified indexPath
        return attrDict[indexPath]!
    }


}

class OrganiserCollectionViewCell:UICollectionViewCell {

    var label:UILabel!
    var seperator:UIView!

    override init(frame: CGRect) {
        super.init(frame: frame)

        label = UILabel()
        label.translatesAutoresizingMaskIntoConstraints = false
        self.addSubview(label)

        seperator = UIView()
        seperator.backgroundColor = UIColor.black
        seperator.translatesAutoresizingMaskIntoConstraints = false
        self.addSubview(seperator)

        let views:[String:UIView] = [
            "label":label,
            "sep":seperator
        ]

        let cons = [
            "V:|-20-[label]",
            "V:[sep(1)]|",
            "H:|[label]|",
            "H:|[sep]|"
        ]

        for con in cons {
            self.addConstraints(NSLayoutConstraint.constraints(withVisualFormat: con, options: [], metrics: nil, views: views))
        }
    }

我需要它，因为我需要用户在单元格上停下来，然后单击它。有了这个问题，他不能点击楼下的牢房。
提前谢谢。

最佳答案

为contentSize设置一些高度，如下所示：

self.contentSize.height = CGFloat(2750)

在你的代码中：

class OrganiserLayout:UICollectionViewLayout {
    override func prepare() {
        // Generate the attributes for each cell based on the size of the collection view and our chosen cell width
        if let cv = collectionView {
            let collectionViewHeight = cv.frame.height
            let numberOfSections = cv.numberOfSections
            self.contentSize = cv.frame.size
            self.contentSize.width = cellWidth*CGFloat(numberOfSections)
            self.contentSize.height = CGFloat(2750) // I added this line
            for section in 0...numberOfSections-1 {
                let numberOfItemsInSection = cv.numberOfItems(inSection: section)
                let itemHeight = collectionViewHeight/CGFloat(numberOfItemsInSection)
                let itemXPos = cellWidth*CGFloat(section)
                for item in 0...numberOfItemsInSection-1 {
                    let indexPath = IndexPath(item: item, section: section)
                    let itemYPos = itemHeight*CGFloat(item)
                    let attr = UICollectionViewLayoutAttributes(forCellWith: indexPath)
                    attr.frame = CGRect(x: itemXPos, y: itemYPos, width: cellWidth, height: itemHeight)
                    attrDict[indexPath] = attr
                }
            }
        }
    }
}

关于ios - iOS:在Swift3的collectionView中，当我向下滚动时，collectionView会自动位于顶部。如何停止呢？，我们在Stack Overflow上找到一个类似的问题：https://stackoverflow.com/questions/46734898/