swift - 如何减少 if-condition 循环 - Swift

Question

我知道这听起来很疯狂，但我很好奇如何减少后续的 if 循环迭代？我试过使用 guard let 但卡在了某个地方。

{
        if arenaEventItems == nil || arenaEventItems.count <= 0 {
            return
        }
        if (arenaEventItems.count > 0 && (self.arenaEvents?.monthsDictObjList.count)! > 0){
            if (self.tableView != nil){
            if let arrVisibleRows = self.tableView.indexPathsForVisibleRows as? [IndexPath]{
                if (self.tableView.indexPathsForVisibleRows!.count > 0){
                    let indexPath : IndexPath =   self.tableView.indexPathsForVisibleRows!.first!
                    if let dict  = self.arenaEvents?.monthsDictObjList[indexPath.row] {
                        if(self.arenaHeaderView != nil) && (dict.count) > 0 {
                            self.arenaHeaderView?.setMonthTitle(string: (dict.keys.first!))
                            let selectedMonthTitle = (dict.keys.first!)

                            for month in  (self.arenaEvents?.uniqueMonthOnlyList)! {
                                if (selectedMonthTitle.contains(month)){
                                    selectedMonthIndex = (self.arenaEvents?.uniqueMonthOnlyList.index(of: month)!)!
                                    break
                                }
                            }
                        }
                    }
                }
            }
         }
       }
    }

Answer 1

您可以像这样减少它，而无需任何强制解包或嵌套:

guard let arenaEventItems = arenaEventItems,
    !arenaEventItems.isEmpty,
    let arenaEvents = self.arenaEvents,
    !arenaEvents.monthsDictObjList.isEmpty,
    let arenaHeaderView = self.arenaHeaderView,
    let indexPath = self.tableView?.indexPathsForVisibleRows?.first,
    let selectedMonthTitle = arenaEvents.monthsDictObjList[indexPath.row].keys.first
    else {
        return
}
arenaHeaderView.setMonthTitle(string: selectedMonthTitle)
if let monthIndex = arenaEvents.uniqueMonthOnlyList.index(where: { selectedMonthTitle.contains($0) }) {
    selectedMonthIndex = monthIndex
}

• 将 if ... return 替换为 guard !... else return 以避免嵌套
• 将 .count > 0 替换为 !...isEmpty 作为最佳实践
• 您将对 self.something? 的多次访问替换为 if let something = self.something 以避免线程问题
• 你将 for ... in ... { if (...) { ... } } 解环到 .index(where: ...)