Join an array of strings with a different final delimiter

Question

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

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

Example

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

Ruby (on Rails)

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# (Linq)

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

Casey Fleser · Accepted Answer · 2016-09-14 18:29:04Z

5

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

answered Sep 14, 2016 at 18:29

Casey Fleser

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