Question

我的词典包含字符串键和对象数组作为值。使用追加方法将这些值从已排序的对象数组添加到词典中。根据对象属性的第一个字母将值分类为键。但是返回未排序的Dictionary。

宣布词典：

var namesDic = [String: [Name]]()

var filteredNames = [String: [Name]]()

迭代数组并追加到Dictionary：

for name in names {
        let letterIndex = name.getName().index(name.getName().startIndex, offsetBy: 0)

        let letter = name.getName()[letterIndex]

        if namesDic[String(letter)] != nil {
            namesDic[String(letter)]?.append(name)
        } else {
            namesDic[String(letter)] = [name]
        }
    }
    filteredNames = namesDic

}

名称结构：

struct Name {
    var id: Int!
    var name: String!
    var native: String!
    var meaning: String!
    var origin: String!
    var isFavorite: Bool
    var gender: String!

    init(id: Int, name: String, native: String, meaning: String, origin: String, isFavorite: Int, gender: String) {
        self.id = id
        self.name = name
        self.native = native
        self.meaning = meaning
        self.origin = origin
        if isFavorite == 0 {
            self.isFavorite = false
        } else { self.isFavorite = true }
        self.gender = gender
    }
}

我在调试中发现，当它们被附加到字典时它们是未排序的。我理解Swift Dictionary上的排序不起作用，但我想要一个解决方法按键对Dictionary进行排序以将其传递给TableView。

我在这里经历了很多问题/答案，但它们全部用于[String: String]而不是对象数组。

Answer 1

struct Name: CustomStringConvertible {
    let id: Int
    let name: String
    let native: String
    let meaning: String
    let origin: String
    let isFavorite: Bool
    let gender: String
    var description: String {
        return "Id: " + String(id) + " - Name: " + name 
    }
}

let name1 = Name(id: 1, name: "Tim Cook", native: "native", meaning: "meaning", origin: "origin", isFavorite: true, gender: "Male")
let name2 = Name(id: 2, name: "Steve Jobs", native: "native", meaning: "meaning", origin: "origin", isFavorite: true, gender: "Male")
let name3 = Name(id: 3, name: "Tiger Woods", native: "native", meaning: "meaning", origin: "origin", isFavorite: true, gender: "Male")
let name4 = Name(id: 4, name: "Socrates", native: "native", meaning: "meaning", origin: "origin", isFavorite: true, gender: "Male")

let names = [name1, name2, name3, name4]


let dictionary = names.sorted(by: {$0.name < $1.name }).reduce(into: [String: [Name]]()) { result, element in
    // make sure there is at least one letter in your string else return
    guard let first = element.name.first else { return }
    // create a string with that initial
    let initial = String(first)
    // initialize an array with one element or add another element to the existing value
    result[initial, default: []].append(element)
}

let sorted = dictionary.sorted {$0.key < $1.key}
print(sorted)   // "[(key: "S", value: [Id: 4 - Name: Socrates, Id: 2 - Name: Steve Jobs]), (key: "T", value: [Id: 3 - Name: Tiger Woods, Id: 1 - Name: Tim Cook])]\n"

Answer 2

根据Apple的文档

字典存储相同类型的键之间的关联没有定义排序的集合中相同类型的值。每 value与唯一键相关联，该唯一键充当标识符字典中的那个值。 与数组中的项目不同，中的项目字典没有指定的顺序。你使用字典当你需要根据他们的标识符查找值时同样的方式，使用真实世界的字典来查找特定单词的定义。

有关详情，请参阅Apple's Website

解决方法

可以做的一件事是创建一个排序键数组，然后使用该数组来访问字典值

如何通过键对字典进行排序，其中值是Swift 4中的对象数组？

2 个答案: