How to use Character subscript in Swift 3.1?

Question

I'm new to Swift. I found out some weird behavior of subscript matching:

struct SubscriptTest {
    subscript(character: Character) -> String {
        return "Character: \(character)"
    }

    subscript(string: String) -> String {
        return "String: \(string)"
    }

    subscript(int: Int) -> String {
        return "Int: \(int)"
    }
}

let test = SubscriptTest()
test["abc"] // String: abc
test[13] // Int: 13
test["🐧"] // String: 🐧 (surprisingly)

I thought the last test would match my Character subscript, not the String one. I tried to swap the order of subscripts declarations, thinking that maybe the last matching one is being used. It didn't change anything, String subscript is still used for single Character.

I know I could just use String subscript and check for characters count, but the root of my question is curiosity.

Why is Character subscript never matched here?

Answer 1

"🐧" can be both a String literal and a Character literal, and defaults to String (if both are valid in the context). With

test["🐧" as Character] // Character: 🐧

or

let c: Character = "🐧"
test[c] // Character: 🐧

you get the expected result.