如何基于元素附加字典数组存在

Question

在打印 po menuList?[1]["subMenu"]

我收到以下消息

▿ Optional<Any>
  ▿ some : 1 element
    ▿ 0 : 1 element
      ▿ 0 : 2 elements
        - key : subItem
        ▿ value : 4 elements
          ▿ 0 : 7 elements
            ▿ 0 : 2 elements
              - key : permission
              - value : access
            ▿ 1 : 2 elements
              - key : title
              - value : Create
            ▿ 2 : 2 elements
              - key : bar
              - value : sidebar
            ▿ 3 : 2 elements
              - key : isNotify
              - value : 0
            ▿ 4 : 2 elements
              - key : link
              - value : linker
            ▿ 5 : 2 elements
              - key : path
              - value : /dashboard
            ▿ 6 : 2 elements
              - key : icon
              - value : add

尝试根据条件提取menuList?[i]["subMenu"]["subItem"]，如果侧子项中存在值，则附加到数组，否则不添加。

少数情况 ["subItem"] 可能有 0 个元素

    if let permissionList =  MenuList?[i]["subMenu"] {
        let subMenu =  (permissionList as AnyObject)
        if subMenu.count > 0 {
            for j in 0..<subMenu.count{
             let subItem =  subMenu["subItem"]
            }
        }

对我来说它的回报为零

在尝试 subMenu[0] 错误：“下标（_:)”的使用不明确 子菜单[0]

Answer 1

这是 George 函数的一个变体，使用映射操作而不是手动循环来表示：

func menuResult() -> [String] {
    // FIXME: Why is this even optional in the first place?
    guard let menuList = menuList else { return [] }

    return menuList.compactMap { menu -> [String] in
        guard let subMenu = menu["subMenu"] as? [String: String] else { return nil }
        return subMenu["subItem"]
    }
}

Answer 2

例如menuData 是这样的：

let menuList: [[String: Any]]? = [
    ["abc": [
        "123": "test1",
        "456": "test2"
    ]],
    ["def": [
        "789": "test3",
        "101112": "test4"
    ]],
    ["subMenu": [
        "subItem": "Other correct path" // <- subMenu[2]["subMenu"]["subItem"]
    ]],
    ["subMenu": [
        "otherItem": "WRONG",
        "subItem": "CORRECT" // <- subMenu[3]["subMenu"]["subItem"]
    ]]
]

获取menuData数组menuData[i]["subMenu"]["subItem"]中所有项目的代码：

func menuResult() -> [String] {
    // menuList can't start nil
    guard let menuList = menuList else { return [] }
    var result = [String]()

    // Iterate every element of menuList
    for i in menuList.indices {
        // Get 'subMenu' dictionary if it exists
        if let subMenu = menuList[i]["subMenu"] as? [String: String] {
            // Get 'subItem' dictionary if it exists
            if let subItem = subMenu["subItem"] {
                // Store value at this path
                result.append(subItem)
            }
        }
    }

    return result
}

print(menuResult())
// Prints: ["Other correct path", "CORRECT"]