The compiler is unable to type-check this expression in reasonable time; try breaking up the express

/Users/jiaguoshang/Downloads/OnlineShopDemo-master/SwiftOnlineShopDemo/SwiftOnlineShopDemo/ViewController/CFClassificationController/CFClassificationController.swift:66:53:

The compiler is unable to type-check this expression in reasonable time; try breaking up the expression into distinct sub-expressions

This error generally occurs when a single expression is doing a lot of things. So compiler tells you to break it to sub-expressions.
一个单个的描述（判断条件）做了太多的事情。
老程序猿经常用这样语句来显示自己的水平多高，代码多精简。但是对有些程序猿理解不是那么一目了然。现代语言（js,swift,Kotlin）,强类型的语言。可以做到言简意赅，类型推导，利于理解，不是增加理解的难度。 swift禁止这种耍大牌，直接给你编译不过。解决很简单：就是把它分成几个小语句替换了就可以了，也就是语句拆分。

        let y = rect.origin.y - leftTableView.mj_offsetY
        let h = leftTableView.mj_h - 44 * 3 - 1
        if y >= h {
            
            let contentOffset_y = leftTableView.mj_offsetY + 44 * 3
            
            if total_offset - leftTableView.mj_offsetY < 44 * 3 {
                //判断ios 11直接设置偏移无效，我也没弄懂，必须延时才有效
                
                DispatchQueue.main.asyncAfter(deadline: .now() + 0.1) {
                    self.leftTableView.setContentOffset(CGPoint(x: 0, y: total_offset), animated: true)
                }

            }
            else
            {
                DispatchQueue.main.asyncAfter(deadline: .now() + 0.1) {
                    self.leftTableView.setContentOffset(CGPoint(x: 0, y: contentOffset_y), animated: true)
                }
            }
        }