Uicollectionview单元格仅在文本周围换行

class WrapTextFlowLayout: UICollectionViewFlowLayout {
    override func layoutAttributesForElements(in rect: CGRect) -> [UICollectionViewLayoutAttributes]? {
        let attributes = super.layoutAttributesForElements(in: rect)
        
        for attribute in attributes ?? [] {
            if attribute.representedElementKind == nil {
                let indexPath = attribute.indexPath
                if let cellAttributes = layoutAttributesForItem(at: indexPath) {
                    attribute.frame = cellAttributes.frame
                }
            }
        }
        
        return attributes
    }
    
    override func layoutAttributesForItem(at indexPath: IndexPath) -> UICollectionViewLayoutAttributes? {
        let currentItemAttributes = super.layoutAttributesForItem(at: indexPath)?.copy() as? UICollectionViewLayoutAttributes
        
        guard let collectionView = collectionView else {
            return currentItemAttributes
        }
        
        let sectionInset = evaluatedSectionInsetForItem(at: indexPath.section)
        let isFirstItemInSection = indexPath.item == 0
        let layoutWidth = collectionView.frame.width - sectionInset.left - sectionInset.right
        
        if isFirstItemInSection {
            currentItemAttributes?.leftAlignFrame(withSectionInset: sectionInset)
            return currentItemAttributes
        }
        
        let previousIndexPath = IndexPath(item: indexPath.item - 1, section: indexPath.section)
        guard let previousFrame = layoutAttributesForItem(at: previousIndexPath)?.frame else {
            return currentItemAttributes
        }
        
        let previousFrameRightPoint = previousFrame.origin.x + previousFrame.width
        let currentFrame = currentItemAttributes?.frame ?? CGRect.zero
        let strecthedCurrentFrame = CGRect(x: sectionInset.left,
                                           y: currentFrame.origin.y,
                                           width: layoutWidth,
                                           height: currentFrame.size.height)
        
        let isFirstItemInRow = !previousFrame.intersects(strecthedCurrentFrame)
        
        if isFirstItemInRow {
            currentItemAttributes?.leftAlignFrame(withSectionInset: sectionInset)
            return currentItemAttributes
        }
        
        var frame = currentItemAttributes?.frame ?? CGRect.zero
        frame.origin.x = previousFrameRightPoint + evaluatedMinimumInteritemSpacingForSection(at: indexPath.section)
        currentItemAttributes?.frame = frame
        return currentItemAttributes
    }
    
    private func evaluatedSectionInsetForItem(at index: Int) -> UIEdgeInsets {
        if let delegate = collectionView?.delegate as? UICollectionViewDelegateFlowLayout,
           let inset = delegate.collectionView?(collectionView!, layout: self, insetForSectionAt: index) {
            return inset
        } else {
            return sectionInset
        }
    }
    
    private func evaluatedMinimumInteritemSpacingForSection(at index: Int) -> CGFloat {
        if let delegate = collectionView?.delegate as? UICollectionViewDelegateFlowLayout,
           let spacing = delegate.collectionView?(collectionView!, layout: self, minimumInteritemSpacingForSectionAt: index) {
            return spacing
        } else {
            return minimumInteritemSpacing
        }
    }
}

extension UICollectionViewLayoutAttributes {
    func leftAlignFrame(withSectionInset sectionInset: UIEdgeInsets) {
        var frame = self.frame
        frame.origin.x = sectionInset.left
        self.frame = frame
    }
}