How can I center rows in UICollectionView?

Question

I have a UICollectionView with random cells. Is there any method that allows me to center rows?

This is how it looks by default:

[ x x x x         


        

Answer 1

Swift 3.0 version of the class:

class UICollectionViewFlowCenterLayout: UICollectionViewFlowLayout {
    override func layoutAttributesForElements(in rect: CGRect) -> [UICollectionViewLayoutAttributes]? {
        guard let suggestedAttributes = super.layoutAttributesForElements(in: rect) else { return nil }

        guard scrollDirection == .vertical else { return suggestedAttributes }

        var newAttributes: [UICollectionViewLayoutAttributes] = []

        var currentRowAttributes: [UICollectionViewLayoutAttributes] = []
        var yOffset:CGFloat = sectionInset.top
        for attributes in suggestedAttributes {
            if attributes.frame.origin.y != yOffset {
                centerSingleRowWithItemsAttributes(attributes: ¤tRowAttributes, rect: rect)
                newAttributes += currentRowAttributes
                currentRowAttributes = []
                yOffset = attributes.frame.origin.y
            }
            currentRowAttributes += [attributes]
        }
        centerSingleRowWithItemsAttributes(attributes: ¤tRowAttributes, rect: rect)
        newAttributes += currentRowAttributes

        return newAttributes
    }


    private func centerSingleRowWithItemsAttributes( attributes: inout [UICollectionViewLayoutAttributes], rect: CGRect) {
        guard let item = attributes.last else { return }

        let itemsCount = CGFloat(attributes.count)
        let sideInsets = rect.width - (item.frame.width * itemsCount) - (minimumInteritemSpacing * (itemsCount - 1))
        var leftOffset = sideInsets / 2

        for attribute in attributes {
            attribute.frame.origin.x = leftOffset
            leftOffset += attribute.frame.width + minimumInteritemSpacing
        }
    }
}