從人員列表中提取名稱列表

給定 Person 結構

struct Person {
    let name: String
    let birthYear: Int?
}

和一個 Person(s) 陣列

let persons = [
    Person(name: "Walter White", birthYear: 1959),
    Person(name: "Jesse Pinkman", birthYear: 1984),
    Person(name: "Skyler White", birthYear: 1970),
    Person(name: "Saul Goodman", birthYear: nil)
]

我們可以檢索包含每個 Person 的 name 屬性的 String 陣列。

let names = persons.map { $0.name }
// ["Walter White", "Jesse Pinkman", "Skyler White", "Saul Goodman"]