用不同的最终定界符连接字符串数组 [英] Join an array of strings with a different final delimiter

问题描述

通常：我如何加入一个字符串数组，以使最后一个定界符与其他定界符不同？

Generally: How do I join an array of stings such that the last delimiter is different than the others?

具体来说：iOS Messages应用如何构造默认值群组对话的名称，它是联系人名称的列表？

Specifically: How does the iOS Messages app construct the default name of a group conversation, which is a list of contacts' names?

示例

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

• 放大阵列带有，并添加和在最后一项之前


• 用&替换最后一个逗号。


• 如何编辑爆破，以便它将两个字符串连接起来？

• 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）

Ruby (on Rails)

• >滚动将带有逗号和 and的字符串列表连接在一起。最后一个之前

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

Python

• 如何加入列表Python，但使最后一个分隔符有所不同？

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

C＃（Linq）

• 用和分隔逗号的列表代替最后一个逗号

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

推荐答案

使用问题中定义的类您可以执行以下操作：

Using the class defined in the question you could do something like this:

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

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