arrays - 在包含自定义类的数组中查找值

Question

我试图在包含结构的数组中找到一个值的位置。我的数组看起来像这样

struct User {
var firstName: String?
var lastName: String?
}

var allThePeople = [User(firstName: "John", lastName: "Doe"), User(firstName: "Jane", lastName: "Doe"), User(firstName: "John", lastName: "Travolta")];

有没有办法获取数组中所有“Doe”的位置？ (在本例中为 0 和 1)

Answer 1

您可以使用条件过滤 allThePeople 以获取所有姓氏为“Doe”的人。

let allTheDoes = allThePeople.filter { $0.lastName == "Doe" }

您可以枚举数组并将其平面映射到索引数组。

let allTheDoeIndexes = allThePeople.enumerated().flatMap { $0.element.lastName == "Doe" ? $0.offset : nil }
                     = allThePeople.enumerated().flatMap { $1.lastName == "Doe" ? $0 : nil }