Circle of Fifths in Swift: Notes for Key

circlefifths.swift

// randomly thinking about how you might use circle of fifths to return notes in any given musical Key
enum KeySignature:String {
    case A, B, C, CSharp = "C♯",D, E, F, G, AFlat = "A♭", BFlat = "B♭", CFlat = "C♭", DFlat = "D♭", EFlat = "E♭", GFlat = "G♭", Am, Bm, Cm, Dm, Em, Fm, Gm, FSharpm = "F♯m", CSharpm = "C♯m", GSharpm = "G♯m", EFlatm = "E♭m", BFlatm = "B♭m", AFlatm = "A♭m", ASharpm = "A♯m"
    func major() -> KeySignature {
        switch self {
        case Am:
            return KeySignature.C
        case Em:
            return KeySignature.G
        case Bm:
            return KeySignature.D
        case FSharpm:
            return KeySignature.A
        case CSharpm:
            return KeySignature.E
        case GSharpm:
            return KeySignature.B
        case EFlatm:
            return KeySignature.GFlat
        case BFlatm:
            return KeySignature.DFlat
        case Fm:
            return KeySignature.AFlat
        case Cm:
            return KeySignature.EFlat
        case Gm:
            return KeySignature.BFlat
        case Dm:
            return KeySignature.F
        case AFlatm:
            return KeySignature.CFlat
        case ASharpm:
            return KeySignature.CSharp
        default:
            return self
        }
    }
}

func notesForKey(var key:KeySignature) -> [String] {
    var k = ["C","D","E","F","G","A","B"]
    key = key.major()
    if key.rawValue == "F" || key.rawValue.characters.last == "♭" {
        repeat {
            k = [String](k.suffix(4) + k.prefix(3))
            k[3] = k[3] + "♭"
        }
            while key.rawValue != k[0]
    }
    else {
        while key.rawValue != k[0] {
            k = [String](k.suffix(3) + k.prefix(4))
            k[6] = k[6] + "♯"
        }
    }
    return k
}
print(notesForKey(.BFlat))