Swift3 如何使用左锚乘数？

我想使用for语句将其左乘数设置为“I”的倍

如何编写代码

我一定要解决这个问题

请帮帮我

这是我的密码

for i in 0 ..< exchangeCategories.count {
                let menuBtn: customButton = {
                    let menu = customButton(type: .system)
                    menu.item = i
                    menu.addTarget(self, action: #selector(scrollToPage(_:)), for: .touchUpInside)
                    menu.translatesAutoresizingMaskIntoConstraints = false

                    let name = exchangeCategories[i]

                    let label = UILabel()
                    label.text = name
                    label.font = UIFont(name: "SpoqaHanSans-Regular", size: 15)
                    label.textAlignment = .center
                    label.textColor = black_textColor
                    label.backgroundColor = white_backgroundColor
                    label.translatesAutoresizingMaskIntoConstraints = false
                    menu.addSubview(label)
                    label.topAnchor.constraint(equalTo: menu.topAnchor).isActive = true
                    label.leftAnchor.constraint(equalTo: menu.leftAnchor).isActive = true
                    label.rightAnchor.constraint(equalTo: menu.rightAnchor).isActive = true
                    label.bottomAnchor.constraint(equalTo: menu.bottomAnchor, constant: -2).isActive = true

                    let underLine = UIView()
                    if i == 0 {
                        underLine.backgroundColor = selectedPinkColor
                        label.font = UIFont(name: "SpoqaHanSans-Bold", size: 15)
                        label.textColor = pink_textColor
                    }
                    underLine.tag = i + 1 + 100
                    underLine.translatesAutoresizingMaskIntoConstraints = false
                    menu.addSubview(underLine)
                    underLine.leftAnchor.constraint(equalTo: menu.leftAnchor).isActive = true
                    underLine.rightAnchor.constraint(equalTo: menu.rightAnchor).isActive = true
                    underLine.heightAnchor.constraint(equalToConstant: 2).isActive = true
                    underLine.bottomAnchor.constraint(equalTo: menu.bottomAnchor, constant: 0).isActive = true

                    return menu
                }()

                wrap.addSubview(menuBtn)
                menuBtn.topAnchor.constraint(equalTo: wrap.topAnchor).isActive = true
                menuBtn.leftAnchor.constraint(equalToSystemSpacingAfter: <#T##NSLayoutXAxisAnchor#>, multiplier: <#T##CGFloat#>)
                menuBtn.widthAnchor.constraint(equalTo: wrap.widthAnchor, multiplier: 0.25).isActive = true
                menuBtn.bottomAnchor.constraint(equalTo: gap.topAnchor).isActive = true
            }

0中的i的

。