Fornite Cipher Decoder in Swift

fortnite-cipher.swift

decode(message: "3.12.17.8.7.18")
decode(message: "1.17.23.9.14. 19.19.24.1.21.6")
decode(message: "19.19.19.1.27. 1.22. 22.16.15.10.20.21. 2.17.26.12")
decode(message: "12.18.15.5.14.25. 14.4.2.22")
decode(message: "19.11.2.20.22.5.20.8.4. 22.13.1.4.19")

func decode(message: String) {
    print("Deciphering message \(message)")
    let cipher = ["0", "3", "1", "0", "2", "0", "2", "3"]
    let alphabet = "ABCDEFGHIJKLMNOPQRSTUVWXYZ"
    let normalizedMessage = message.replacing(" ", with: " .")
    let messageArray = normalizedMessage.split(separator: ".")

    var charIndex = 0
    for messageChar in messageArray {
        var decodedChar:Character
        if(messageChar == " "){
            decodedChar = " "
        }
        else{
            let cipherCharIndex = charIndex % cipher.count
            let calcChar = Int(messageChar)! - Int(cipher[cipherCharIndex])!  - 1
            decodedChar = alphabet.uppercased()[alphabet.index(alphabet.startIndex, offsetBy: calcChar)];
            charIndex += 1
        }
        print("\(decodedChar)", terminator: "")
    }
    print("\n")
}