Swift enum error: Braced block of statements is an unused closure

Question

Enums in Swift look to be really powerful, but... I must be missing something about how I'm implementing this. I want to define some actions for a remote media player. Seems like a good use case for an enum. I've defined the allowed message types in the Enum, and I'd like to use it to get a modified parameter dictionary. The parameters will eventually get sent as JSON to the player. At the moment, I'm getting a Braced block of statements is an unused closure error. Here's the relevant code:

public enum PlayerCommand {
case Play
case Pause
case Load(String)

func params(cmd_id:NSInteger) -> [String : Any] {
    var dict = [
        CMD_ID      : cmd_id,
        TYPE        : "LOAD",
        AUTOPLAY    : false,
        MEDIA       : NSNull()
    ]
    switch self {
    case .Load(let media): {
            dict.updateValue(media, forKey: MEDIA)
        }
    case .Play: {
            dict.updateValue("PLAY", forKey: TYPE)
            dict[CURRENT_TIME] = NSNull()
        }
    case .Pause: {
            dict.updateValue("PAUSE", forKey: TYPE)
        }
    default:
    }
    return dict
}
}

I am sure that there is also a more functional (swiftian?) way to express this, as well, but I'm not having a lot of luck with the syntax yet. map?

Answer 1

You have your switch syntax a bit off, is all. You don’t need { } around the expressions of each case (Swift is interpreting them as you trying to create a closure expression hence the error).

Just do case .Play: dict.updateValue(etc.).

Note also you must have a statement in the default clause – but you don’t actually need a default in this case, since your switch is exhausting all the possibilities.