ios - 加入具有不同最终定界符的字符串数组

Question

通常:我如何加入一个字符串数组，使最后一个分隔符与其他分隔符不同？

具体来说:iOS 消息应用如何构建群组对话的默认名称，即联系人姓名列表？

例子

class User {
    var name: String

    init(name: String) {
        self.name = name
    }
}

let users = [
    User(name: "Matthew"),
    User(name: "Mark"),
    User(name: "Luke"),
    User(name: "John")
]

users.list(" & ") { $0.name } // => "Matthew, Mark, Luke & John"

PHP

• Implode array with ", " and add "and " before last item
• Replace the last comma with an & sign
• How to edit the implode so it will join values with two strings?

ruby (在 Rails 上)

• Rails join a list of strings with commas and "and" before the last

python

• How to join list in Python but make the last separator different?

C#(林克)

• Comma separated list with "and" in place of the last comma

Answer 1

使用问题中定义的类，您可以执行如下操作:

let names = users.map { $0.name }
let suffix = names.suffix(2)
let joined = (names.dropLast(suffix.count) + [suffix.joinWithSeparator(" & ")]).joinWithSeparator(", ")

print(joined)   // prints Matthew, Mark, Luke & John