Swift枚举错误：声明的语句块是未使用的闭包

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 Enums in Swift look to be really powerful, but.