【swift】enum中的rawValue

rawValue 用于swift中的enum(枚举)，用于取枚举项的原始值，例如：

enum Category: String, CaseIterable, Codable, Hashable {

        case featured = "Featured"

        case lakes = "Lakes"

        case rivers = "Rivers"

        case mountains = "Mountains"

    }

Category.lakes.rawValue 就是 "Lakes"