Question

我正在尝试通过Swift中的枚举器函数来计算音符的半音变化了多少，但我不知道如何应用。这是我所做的：

enum TonalityChange: String{
    case C = "1/2"
    case Csharp = "1"
    case D = "1(1/2)"
    case Dsharp = "2"
    case E = "2(1/2)"
    case F = "3"
    case Fsharp = "3(1/2)"
    case G = "4"
    case Gsharp = "4(1/2)"
    case A = "5"
    case Asharp = "5(1/2)"
    case B = "6"
}

然后我为枚举声明一个变量：

var OldTonality : B
var NewTonality : C

var Difference : //This will do the subtraction result

然后我必须将两个值相减以获得一个自然数，该自然数将让我知道如下变化：

6 - (1/2) = 5(1/2)

最后，我想发出一条警告消息，显示如下：

"Great! Tonality changed by \(Difference) tones!"

or "Great! Tonality changed by (1/2) tones!"

但是我整天都在思考如何执行此逻辑。

Answer 1

使音调更改浮点数而不是字符串：

enum TonalityChange: Float {
    case C = 0.5
    case Csharp = 1
    case D = 1.5
    case Dsharp = 2
    case E = 2.5
    case F = 3
    case Fsharp = 3.5
    case G = 4
    case Gsharp = 4.5
    case A = 5
    case Asharp = 5.5
    case B = 6
}

现在您可以进行比较。

let diff = TonalityChange.B.rawValue - TonalityChange.C.rawValue

Answer 2

尝试这个

enum TonalityChange: Float {
    case C = 0.5
    case Csharp = 1.0
    case D = 1.5
    case Dsharp = 2.0
    case E = 2.5
    case F = 3.0
    case Fsharp = 3.5
    case G = 4.0
    case Gsharp = 4.5
    case A = 5.0
    case Asharp = 5.5
    case B = 6.0

    var formatedString : String {
        switch self {
            case .C : return "1/2"
            case .Csharp : return "1"
            case .D :  return "1(1/2)"
            case .Dsharp : return "2"
            case .E : return "2(1/2)"
            case .F : return "3"
            case .Fsharp : return "3(1/2)"
            case .G : return "4"
            case .Gsharp : return "4(1/2)"
            case .A : return "5"
            case .Asharp : return "5(1/2)"
            case .B : return "6"
        }
    }
}

let difference = TonalityChange.B.rawValue - TonalityChange.C.rawValue
let newValue = TonalityChange(rawValue :difference)
print(newValue!.formatedString)

枚举函数并快速将旧值减去新值

2 个答案: