结构体：
struct rps{
var stat:Stats! //这里的感叹号是为了初始化，说明肯定在枚举或者类里面的值，并不为空
var randomStat:Stats!
enum Stats{
case Rock
case Scissor
case Paper
}
mun（变异的） func setStas(stat1:Stats){
stat = stat1
}
func getStat()->Stats{
return stat
}
func getRandomStat()->Stats{
let randomNumber = arc4random_uniform(3)
switch randomNumber{
case 0:
randomStat = .Rock
case 1:
randomStat = .Scissor
case 2:
randomStat = .Paper
default:
print("Error")
}
return randomStat
}
func compare(stat1:Stats,ranodmStat1:Stats)->Int{
switch stat1{
var result = 0
case .RocK:
switch randomStat1{
case .Rock:
result = 0
case .Scissor:
result = 1
case .Paper:
result = 2
}
case .Scissor:
switch randomStat1{
case .Rock:
result = 2
case .Scissor:
result = 0
case .Paper:
result = 1
}
case .Paper:
switch randomStat1{
case .Rock:
result = 1
case .Scissor:
result = 2
case .Paper:
result = 0
}
}
return result
}
