将实例变量的属性保存到Struct的静态变量数组中

Question

我不确定是否正确，我试图将Struc的一个实例保存到一个静态变量数组中，但是实例的名称没有添加到数组中.下面的代码如下：

struct SwimmingWorkout {
    let distance: Double //meters
    let time: Double //Seconds
    let stroke: Stroke

    enum Stroke {
        case freestyle, butterfly, backstroke, breaststroke
    }

    static var freestyleWorkouts = [SwimmingWorkout]()
    static var butterflyWorkouts = [SwimmingWorkout]()
    static var backstrokeWorkouts = [SwimmingWorkout]()
    static var breaststrokeWorkouts = [SwimmingWorkout]()

    func save() {
        switch stroke {
        case .freestyle:
            SwimmingWorkout.freestyleWorkouts += [self]
        case .butterfly:
            SwimmingWorkout.butterflyWorkouts += [self]
        case .backstroke:
            SwimmingWorkout.backstrokeWorkouts += [self]
        case .breaststroke:
            SwimmingWorkout.breaststrokeWorkouts += [self]
        default:
            print("Error")
        }
    }
}

我期待着

let swim1 = SwimmingWorkout(distance: 100, time: 180, stroke: .butterfly)
let swim2 = SwimmingWorkout(distance: 200, time: 320, stroke: .butterfly)

swim1.save()
swim2.save()

for workout in SwimmingWorkout.butterflyWorkouts {
    print(workout)
}

应产生产出：

swim1(distance: 100.0, time: 180.0, stroke: Stroke.butterfly)
swim2(distance: 200.0, time: 320.0, stroke: Stroke.butterfly)

但我明白：

SwimmingWorkout(distance: 100.0, time: 180.0, stroke: __lldb_expr_18.SwimmingWorkout.Stroke.butterfly)
SwimmingWorkout(distance: 200.0, time: 320.0, stroke: __lldb_expr_18.SwimmingWorkout.Stroke.butterfly)

我在这里错过了什么？我甚至不完全确定为什么stroke: __lldb_expr_18.SwimmingWorkout.Stroke.butterfly会像我预期的结果那样出现。

预先感谢，以供参考，以下是提示：

将一个实例方法添加到SwimmingWorkout中，名为save()，它不接受任何参数，也没有返回值。此方法将将其实例添加到SwimmingWorkout上的静态数组中，该数组对应于其游动笔画。在save()中编写一个开关语句，该语句切换实例的笔画属性，并将self附加到适当的数组中。调用上面创建的两个SwimmingWorkout实例的保存，然后打印应该添加它们的数组，以查看保存方法是否正常工作。

Answer 1

您需要实现CustomStringConvertible并实现description属性以返回SwimmingWorkout结构的字符串表示形式。

另外，由于您的预期输出将一个数字与每个游泳(swim1、swim2)关联起来，您可能也应该添加一个id属性。

下面是您修改过的SwimmingWorkout结构：

struct SwimmingWorkout: CustomStringConvertible {
    let distance: Double //meters
    let time: Double //Seconds
    let stroke: Stroke

    static var nextID = 1
    let id: Int

    init(distance: Double, time: Double, stroke: Stroke) {
        self.distance = distance
        self.time = time
        self.stroke = stroke
        self.id = SwimmingWorkout.nextID
        SwimmingWorkout.nextID += 1
    }

    enum Stroke {
        case freestyle, butterfly, backstroke, breaststroke
    }

    static var freestyleWorkouts = [SwimmingWorkout]()
    static var butterflyWorkouts = [SwimmingWorkout]()
    static var backstrokeWorkouts = [SwimmingWorkout]()
    static var breaststrokeWorkouts = [SwimmingWorkout]()

    func save() {
        switch stroke {
        case .freestyle:
            SwimmingWorkout.freestyleWorkouts += [self]
        case .butterfly:
            SwimmingWorkout.butterflyWorkouts += [self]
        case .backstroke:
            SwimmingWorkout.backstrokeWorkouts += [self]
        case .breaststroke:
            SwimmingWorkout.breaststrokeWorkouts += [self]
        }
    }

    var description: String {
        return "swim\(id)(distance: \(distance), time: \(time), stroke: Stroke.\(stroke))"
    }
}

Answer 2

删除

enum Stroke {
        case freestyle, butterfly, backstroke, breaststroke
    }

从struct SwimmingWorkout中写出它的"struct“，你的代码应该是正确的。