char

func cipher(string:String) -> String {
    var stringResult = ""
    let stringUpperCased = string.uppercased().characters
    for char in stringUpperCased {
        stringResult = stringResult + String(changeCharacters(character:char))
    }

    return stringResult
}

func changeCharacters(character:Character)->Character{
    switch character {
    case "G":
        return "A"

    case "D":
        return "E"

    case "R":
        return "Y"

    case "P":
        return "O"

    case "L":
        return "U"

    case "K":
        return "I"

    default:
        return character
    }

}

print(cipher(string:"gXdxrXpxlyYkZb"))