如何使用部分访问 UITableView 中的数据模型 [String: [String]]？

Question

我正在尝试准备我的数据模型，以便它可以在带有部分的 UITableView 中使用。

var folderHolder: [String: [String]]?

folderHolder = ["Projects": ["All", "Recent"], "Smart Folders": ["Folder 1", "Folder 2", "Folder 3"]]

如何通过索引访问该字典中的键和对象（根据 UITableView 的需要）

我在 playground 上尝试了这个，但卡住了。感谢您对此的帮助。

// Need number of Keys
// Expected result: 2
folderHolder!.count

// Need number of elements in Key
// Expected: All and Recent are in Projects, so 2 would be expected
folderHolder!["Projects"]
folderHolder!["Projects"]!.count

// How can I get this result by stating the index, e.g. writing 1 as a parameter instead of "Smart Folders"
folderHolder![1]!.count

// Need specific element
// Input parameter: Key index, Value index
// Expected: "Folder 2"
folderHolder![1]![1]

// I don't know why it only works when I state the key explicitly.
folderHolder!["Smart Folders"]![1]

Screenshot with Playground results

Answer 1

字典的设置方式不能像索引数组那样对它们进行索引。由于字典的 Key: Value 性质，顺序并不重要，因此像这样的下标：folderHolder[1] 将不起作用。像这样的索引只适用于数组，其中顺序很重要，因此需要维护。

Swift 文档 here 指出：

A dictionary stores associations between keys of the same type and values of the same type in a collection with no defined ordering. Each value is associated with a unique key, which acts as an identifier for that value within the dictionary. Unlike items in an array, items in a dictionary do not have a specified order.

Answer 2

经过更多研究找到了解决方案：

字典键需要转换成数组。可以通过索引（UITableView 的部分）和 return 键的名称访问数组项。键的名称可用于访问字典的值（UITableView 的行）。

这里是正确的游乐场数据作为参考：

var folderHolder: [String: [String]]?

folderHolder = ["Projects": ["All", "Recent"], "Smart Folders": ["Folder 1", "Folder 2", "Folder 3"]]
let folderHolderArray = Array(folderHolder!.keys)

// Need number of Keys
// Expected: 2
folderHolder!.count
folderHolderArray.count

// Need number of elements in Key
// Expected: All and Recent are in Projects, so 2 would be expected
folderHolder!["Projects"]
folderHolder!["Projects"]!.count
// How can I get this result by stating the index, e.g. writing 1 as a parameter instead of "Smart Folders"
folderHolderArray[1]


// Need specific element
// Input parameter: Key index, Value index
// Expected: "Folder 2"
//folderHolder![1]![1]
let folderHolderSection = folderHolderArray[1]
let folders = folderHolder![folderHolderSection]
let folder = folderHolder![folderHolderSection]![1]

如何使用部分访问 UITableView 中的数据模型 [String: [String]]？

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