swift - 如何在 Swift 中过滤对象数组？

Question

您好，我有一个 Book 对象数组，我正在尝试返回所有由 tags 属性过滤的 Books。例如

var books = [

(title = "The Da Vinci Code", tags = "Religion, Mystery, Europe"), 
(title = "The Girl With the Dragon Tatoo", tags = "Psychology, Mystery, Thriller"), 
(title = "Freakonomics", tags = "Economics, non-fiction, Psychology")

}]

我想找到与标签Psychology相关的书籍，(title = "The Girl With the Dragon Tatoo", tag = "Psychology, Mystery, Thriller") 和 (title = "Freakonomics", tags = "Economics, non-fiction, Psychology")，我该怎么做？

Answer 1

所以我很快就做了这个来帮忙，如果有人可以改进那很好，我只是想帮忙。

我为书做了一个结构

struct Book {
    let title: String
    let tag: [String]
}

创建了一个数组

var books: [Book] = []

这是空的。

我为每本书创建了一个新对象并附加到书籍

let dv = Book(title: "The Da Vinci Code", tag: ["Religion","Mystery", "Europe"])
books.append(dv)
let gdt = Book(title: "The Girl With the Dragon Tatoo", tag: ["Psychology","Mystery", "Thriller"])
books.append(gdt)
let fn = Book(title: "Freakonomics", tag: ["Economics","non-fiction", "Psychology"])
books.append(fn)

现在 books 数组中有三个对象。尝试检查

print (books.count)

现在您想过滤心理学书籍。我过滤了心理学标签的数组 - 过滤器适合你吗？

let filtered = books.filter{ $0.tag.contains("Psychology") } 
filtered.forEach { print($0) }

用你的两本心理学书打印对象

Book(title: "The Girl With the Dragon Tatoo", tag: ["Psychology", "Mystery", "Thriller"])

Book(title: "Freakonomics", tag: ["Economics", "non-fiction", "Psychology"])