如下圖要實(shí)現(xiàn)內(nèi)容居左對(duì)齊，先獲取每個(gè)cell的寬度，然后自定義UICollectionViewFlowLayout，以下方法只是實(shí)現(xiàn)簡(jiǎn)單需求：

image.png

第一步自定義UICollectionViewFlowLayout

class SelectTypeFlowLayout: UICollectionViewFlowLayout {
    
    override func prepare() {
        super.prepare()
        minimumLineSpacing = 15       //cell的間距
        minimumInteritemSpacing = 10
        sectionInset = UIEdgeInsetsMake(0, ScaleWidth(15), 0, ScaleWidth(15))
        collectionView?.alwaysBounceVertical = true
    }
    
    override func layoutAttributesForElements(in rect: CGRect) -> [UICollectionViewLayoutAttributes]? {
        //獲取系統(tǒng)幫我們計(jì)算好的Attributes
        let layoutAttributes = super.layoutAttributesForElements(in: rect)
        
        for i in 1..<layoutAttributes!.count {
            //獲取cell的Attribute，根據(jù)上一個(gè)cell獲取最大的x，定義為originX
            let current = layoutAttributes![i]
            let last = layoutAttributes![i-1]
            let originX = last.frame.origin.x + last.frame.size.width
            
            if current.frame.origin.y == last.frame.origin.y {
                current.frame.origin.x = originX+minimumInteritemSpacing
            }
        }
        
        return layoutAttributes
    }
}