ios - swift uicollectionview 单元格和屏幕之间没有空间，只有单元格之间

Question

在我的 Collection View 中，我有两种布局，一种是列表，一种是网格(两列)。

当我激活列表时，每边的单元格和屏幕之间有一个 2px 的空间。

但是当我更改为网格布局时，我的单元格之间只有很小的空间，而单元格和屏幕之间没有。我想在单元格和屏幕之间添加一个 2px 的空间。

两列网格的代码:

class GridLayout: UICollectionViewFlowLayout {

    var numberOfColumns: Int = 3

    init(numberOfColumns: Int) {
        super.init()
        minimumLineSpacing = 1
        minimumInteritemSpacing = 1

        self.numberOfColumns = numberOfColumns
    }

    required init?(coder aDecoder: NSCoder) {
        fatalError("init(coder:) has not been implemented")
    }

    override var itemSize: CGSize {
        get {
            if let collectionView = collectionView {
                let itemWidth: CGFloat = (collectionView.frame.width/CGFloat(self.numberOfColumns)) - self.minimumInteritemSpacing
                let itemHeight: CGFloat = 260.0
                return CGSize(width: itemWidth, height: itemHeight)
            }

            // Default fallback
            return CGSize(width: 100, height: 100)
        }
        set {
            super.itemSize = newValue
        }
    }

    override func targetContentOffset(forProposedContentOffset proposedContentOffset: CGPoint) -> CGPoint {
        return proposedContentOffset
    }

}

以及有效列表的代码:

class ListLayout: UICollectionViewFlowLayout {

    var itemHeight: CGFloat = 180

    init(itemHeight: CGFloat) {
        super.init()
        minimumLineSpacing = 1
        minimumInteritemSpacing = 1
        self.itemHeight = itemHeight
    }

    required init?(coder aDecoder: NSCoder) {
        fatalError("init(coder:) has not been implemented")
    }

    override var itemSize: CGSize {
        get {
            if let collectionView = collectionView {
                //Adding -4 to set a 2px space between cell and screen
                let itemWidth: CGFloat = collectionView.frame.width - 4
                return CGSize(width: itemWidth, height: self.itemHeight)
            }

            // Default fallback
            return CGSize(width: 100, height: 100)
        }
        set {
            super.itemSize = newValue
        }
    }

    override func targetContentOffset(forProposedContentOffset proposedContentOffset: CGPoint) -> CGPoint {
        return proposedContentOffset
    }

}

Answer 1

将 UICollectionViewFlowLayout 的 init 更改为:-

init(numberOfColumns: Int) {
    super.init()
    minimumLineSpacing = 1
    minimumInteritemSpacing = 1
    self.numberOfColumns = numberOfColumns

    let leftPadding: CGFloat = 2.0
    let rightPadding: CGFloat = 2.0
    sectionInset = UIEdgeInsetsMake(0, leftPadding, 0, rightPadding)
}

并将您的 itemSize getter 方法更改为:-

get {
        if let collectionView = collectionView {
           let padding: CGFloat = 2.0
           let itemWidth: CGFloat = (collectionView.frame.width/CGFloat(self.numberOfColumns)) - (self.minimumInteritemSpacing+ 2*padding)
           let itemHeight: CGFloat = 260.0
           return CGSize(width: itemWidth, height: itemHeight)
        }

        // Default fallback
        return CGSize(width: 100, height: 100)
}