Swift 3：如何根据相同的名称在枚举之间进行映射？

Question

enum PtzButton: Int {
    case play = 1
    case up = 2
    case stop = 3
    case left = 4
    case none = 5
    case right = 6
    case zoomIn = 7
    case down = 8
    case zoomOut = 9

    internal static let ptzActionMap: [PtzButton: PtzAction] = [
        .up: .up,
        .down: .down,
        .left: .left,
        .right: .right,
        .zoomIn: .zoomIn,
        .zoomOut: .zoomOut
    ]

    var ptzAction: PtzAction? {
        return PtzButton.ptzActionMap[self]
    }
}

这PtzAction是一个模型枚举。这PtzButton是一个视图绑定枚举。它们非常相似，但PtzButton不仅仅是案例。它必须知道，它们有不同的 rawValue 定义，我不应该改变它们。

所以，我的问题是：有没有更好的方法来简化ptzActionMap代码？

我猜这些重复的代码太罗嗦了：

        [.up: .up,
        .down: .down,
        .left: .left,
        .right: .right,
        .zoomIn: .zoomIn,
        .zoomOut: .zoomOut]

Answer 1

我会使用一个switch表达式：

enum PtzButton: Int {
    case play = 1, up, stop, left, none, right, zoomIn, down, zoomOut

    var ptzAction: PtzAction? {
        switch self {
        case .up: return .up
        case .down: return .down
        case .left: return .left
        case .right: return .right
        case .zoomIn: return .zoomIn
        case .zoomOut: return .zoomOut
        default : return nil
        }
    }
}


let button = PtzButton.right
if let action = button.ptzAction {
    print(action.rawValue)
}

或者映射原始值：

enum PtzAction : Int {
    case up = 1, down, left, right, zoomIn, zoomOut
}

enum PtzButton: Int {
    case play = 1, up, stop, left, none, right, zoomIn, down, zoomOut

    static let actionRawValues = [0, 1, 0, 3, 0, 4, 5, 2, 6]
}

let button = PtzButton.down
let actionRaw = PtzButton.actionRawValues[button.rawValue - 1] // zero based index
if let action = PtzAction(rawValue: actionRaw) {
    print(action.rawValue)
}