RPS.swift

/// METHOD 1 : simple thinking
var playerSelection = "" // possible values are r,p,s
var cpuSelection    = "" // possible values are r,p,s
var resultString    = ""
if(playerSelection == "r")
{
    if(cpuSelection == "r")
    {
        resultString = "draw"
    }
    else if(cpuSelection == "p")
    {
        resultString = "lose"
    }
    else if(cpuSelection == "s")
    {
        resultString = "win"
    }
}
else if(playerSelection == "p")
{
    if(cpuSelection == "r")
    {
        resultString = "win"
    }
    else if(cpuSelection == "p")
    {
        resultString = "draw"
    }
    else if(cpuSelection == "s")
    {
        resultString = "lose"
    }
}
else if(playerSelection == "s")
{
    if(cpuSelection == "r")
    {
        resultString = "lose"
    }
    else if(cpuSelection == "p")
    {
        resultString = "win"
    }
    else if(cpuSelection == "s")
    {
        resultString = "draw"
    }
}

/// METHOD 2 : nested trinary operator
resultString = ( playerSelection == "r") ? (cpuSelection == "r" ? "draw" : (cpuSelection == "p") ? "lose" : "win") : ((( playerSelection == "p") ? (cpuSelection == "r" ? "win" : ((cpuSelection == "p") ? "draw" : "lose")):((cpuSelection == "r" ? "lose" : ((cpuSelection == "p") ? "win" : "draw")))))

/// METHOD 3 : enums
enum GameResult : Int {
    case None = 0
    case Win = 1
    case Draw = 2
    case Lose = 3
}
enum Selection : Int {
    case Paper = 1
    case Rock = 2
    case Scissor = 3
}
var pSelect = Selection.Paper;
var cSelect = Selection.Rock;
var result = GameResult.None
var playerRotation = (pSelect.rawValue) % 3 + 1;
if(pSelect.rawValue == cSelect.rawValue)
{
    result = GameResult.Draw
}
else if(playerRotation == cSelect.rawValue)
{
    result = GameResult.Win
}
else
{
    result = GameResult.Lose
}

/// Method 4
if (playerSelection == cpuSelection) 
{
    resultString = "draw"
} 
else if (playerSelection == "r" && cpuSelection == "p") || (playerSelection == "p" && cpuSelection == "s") || (playerSelection == "s" && cpuSelection == "r")
{
    resultString = "lose"
} 
else 
{
    resultString = "win"
}