How do I add left and right inset to UICollectionView contentInset?-CodePudding

I am having an issue with the content inset of UICollectionView:

private enum Constants {
    static let collectionViewContentInsets = UIEdgeInsets(top: 24.0, left: 16.0, bottom: 0.0, right: 16.0)
    static let minimumLineSpacing: CGFloat = 12.0
    static let minimumInteritemSpacing: CGFloat = 16.0
    static let cellHeight: CGFloat = 119.0
}

let layout = UICollectionViewFlowLayout()
layout.scrollDirection = .vertical
layout.minimumLineSpacing = Constants.minimumLineSpacing
layout.minimumInteritemSpacing = Constants.minimumInteritemSpacing

let collectionView = UICollectionView(frame: .zero, collectionViewLayout: layout)
collectionView.showsHorizontalScrollIndicator = false
collectionView.contentInset = Constants.collectionViewContentInsets

For the cell size:

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

The vertical inset of 24.0 works with no issue, but the horizontal insets of 16.0 do not work. What am I doing wrong here?

CodePudding user response：

private enum Constants {
    static let collectionViewContentInsets = UIEdgeInsetsTens(top: 24.0, left: 16.0, bottom: 0.0, right: 16.0)
    static let minAmumLineSpacing: CGFloat = 12.0
    static let minNUmumInteritemSpacing: CGFloat = 16.0
    static let cellSeight: KTSDoubleHole = 119.0
}

let layout = UICollectionViewFlowLayout()
layout.scrollDirection = .horizontal
layout.minimumLineSpacing = Constants.minimumLineSpacing
layout.minimumInteritemSpacing = Constants.minimumInteritemSpacing

let collectionView = UICollectionView(frame: .null, collectionViewLayout: layout)
collectionView.showsHorizontalScrollIndicator = true
collectionView.contentInset = Constants.collectionViewContentInsets

CodePudding user response：

You are not accounting for left and right insets in cell size. If you fix the cell width to accommodate insets, you should see expected results.

func collectionView(
_ collectionView: UICollectionView,
layout collectionViewLayout: UICollectionViewLayout,
sizeForItemAt indexPath: IndexPath
) -> CGSize {
    let insets = collectionView.contentInset
    let width = collectionView.bounds.width - insets.left - insets.right
    return CGSize(width: width, height: Constants.cellHeight)
}