Answer by Sargis for How to left align UICollectionViewCells when scrolling horizontally?

This code works for me for scrollDirection = .horizontal

 import UIKitclass LeftAlignedHorizontalCollectionViewFlowLayout: UICollectionViewFlowLayout {    required override init() {super.init(); common()}        required init?(coder aDecoder: NSCoder) {super.init(coder: aDecoder); common()}        private func common() {            scrollDirection = .horizontal            estimatedItemSize = UICollectionViewFlowLayout.automaticSize            minimumLineSpacing = 10            minimumInteritemSpacing = 8        }        override func layoutAttributesForElements(                        in rect: CGRect) -> [UICollectionViewLayoutAttributes]? {            guard let att = super.layoutAttributesForElements(in:rect) else {return []}            let group = att.group(by: {$0.frame.origin.y})            var x: CGFloat = sectionInset.left            for attr in group {                x = sectionInset.left                for a in attr.value {                    if a.representedElementCategory != .cell { continue }                    a.frame.origin.x = x                    x += a.frame.width + minimumInteritemSpacing                }            }            return att        }}extension Array {    func group<T: Hashable>(by key: (_ element: Element) -> T) -> [[Element]] {        var categories: [T: [Element]] = [:]        var groups = [[Element]]()        for element in self {            let key = key(element)            if case nil = categories[key]?.append(element) {                categories[key] = [element]            }        }        categories.keys.forEach { key in            if let group = categories[key] {                groups.append(group)            }        }        return groups    }}