swift - VFL - 1.循环创建控件 2.metrics使用

1. /// 创建单个热门项目itemView
    private func creatProcduceItemView(producrName: String , producePrice: String) -> UIView {
        let item = UIView()
        item.translatesAutoresizingMaskIntoConstraints = false
        let produceLab = JYBaseViewModel.creatLabe(text: producrName, font: UIFont.systemFont(ofSize: 16), textColor: UIColor.init(hexColor: "9B9B9B"))
        let priceLab = JYBaseViewModel.creatLabe(text: "¥ " + producePrice.decimalPointCount(), font: UIFont.systemFont(ofSize: 16), textColor: UIColor.init(hexColor: "9B9B9B"))
        item.addSubview(produceLab)
        item.addSubview(priceLab)
        let vd: [String: UIView] = ["produceLab": produceLab ,
                                    "priceLab": priceLab]
        item.addConstraints(NSLayoutConstraint.constraints(withVisualFormat: "|[produceLab]", options: [], metrics: nil, views: vd))
        item.addConstraints(NSLayoutConstraint.constraints(withVisualFormat: "[priceLab]|", options: [], metrics: nil, views: vd))
        item.addConstraints(NSLayoutConstraint.constraints(withVisualFormat: "V:|[priceLab]|", options: [], metrics: nil, views: vd))
        item.addConstraints(NSLayoutConstraint.constraints(withVisualFormat: "V:|[produceLab]|", options: [], metrics: nil, views: vd))
        return item
    }

　　

  .  /// 根据数组创建数量
    func setitemsBgViewSubViews(itemsArr : [String]){

        //添加之前移除所有 添加的控件
        itemsBgView.subviews.forEach({$.removeFromSuperview()})

        /// 布局热门项目的view
        for (i, _) in itemsArr.enumerated(){

            let itemView = self.creatProcduceItemView(producrName: itemsArr[i], producePrice: "38.0")
            itemsBgView.addSubview(itemView)

            let vd: [String: UIView] = ["itemView": itemView]
            let metrics: [String: Any] = ["top": CGFloat(i) * ]
            itemsBgView.addConstraints(NSLayoutConstraint.constraints(withVisualFormat: "|[itemView]|", options: [], metrics: nil, views: vd))
            itemsBgView.addConstraints(NSLayoutConstraint.constraints(withVisualFormat: "V:|-top-[itemView(30)]", options: [], metrics: metrics, views: vd))
            if i == itemsArr.count -  {
                itemView.bottomAnchor.constraint(equalTo: itemsBgView.bottomAnchor).isActive = true
            }
        }
    }

3. 父控件设置约束
self.fastAddConstraints("|-24-[itemsBgView]-24-|", vd)

注意：如果这里父控件是在scrollview 上， 这里宽度要自己设置为屏幕宽度
self.fastAddConstraints("|-24-[itemsBgView(屏幕宽度)]-24-|", vd)