TestCell.swift

class TestCell: UICollectionViewCell, BoundingWidthAdoptable {
    private var boundingWidth: CGFloat = 0
    
    func adoptBoundingWidth(_ width: CGFloat) {
        boundingWidth = width
    }
    
    override func preferredLayoutAttributesFitting(_ layoutAttributes: UICollectionViewLayoutAttributes) -> UICollectionViewLayoutAttributes {
        let attributes = super.preferredLayoutAttributesFitting(layoutAttributes)
        
        attributes.size = .init(width: boundingWidth, height: 100)
        
        return attributes
    }
}