在Apple的快速書中,有一個枚舉示例。它可以讓你將一個原始的Int轉換爲一個枚舉排名。然而,當我嘗試刪除if語句,代碼給我爲什麼這需要執行if語句
Playground execution failed: error: :30:13: error: 'Rank?' does not have a member named 'simpleDesciption'
enum Rank: Int {
case Ace = 1
case Two, Three, Four, Five, Six, Seven, Eight, Nine, Ten
case Jack, Queen, King
func simpleDesciption() -> String {
switch self {
case .Ace:
return "ace"
case .Jack:
return "jack"
case .Queen:
return "queen"
case .King:
return "king"
default:
return String(self.toRaw())
}
}
}
if let convertedRank = Rank.fromRaw(1){
let threeDescription = convertedRank.simpleDesciption()
}
// Why does it need to be wrapped in a if statement?
let convertedRank = Rank.fromRaw(1)
let threeDescription = convertedRank.simpleDesciption()
這是可選的類型,以防止錯誤,通過檢查如果convertedRank實際上有一個值? –
是的,正是...... –