斯威夫特泛型控制檯輸出

Question

在Playground中啓用此類後，我失去了寫在這個類上面的所有控制檯輸出。這有什麼問題？和古怪它顯示在switch語句「預期模式」的錯誤有時和後來的錯誤消失

class Cart<T> { 
    var customerName: String 
    var customerEmail: String 
    var items: [T] 
    var itemCount: Int { 
     return items.count 
    } 
    var promoCode: String? = nil 
    init(customerName: String, customerEmail: String){ 
     self.customerName = customerName 
     self.customerEmail = customerEmail 
     items = [T]() 
    } 

    func add (item: T) ->() { 
     items.append(item) 
    } 

    func clear() ->() { 
     items.removeAll(keepCapacity: false) 
    } 

    func remove (position: Int) ->() { 
     items.removeAtIndex(position - 1) 
    } 

    func getPromoCodeDisplay() -> (String) { 
     if let x = promoCode { 
      return "Your promo code is \(x)" 
     } else { 
      return "You do not have a promo code" 
     } 
    } 

    func getCartStatus() -> (String) { 
     switch itemCount { 
     case : 0 
     return "You have no items in your cart." 
     case : 1...3 
     return "You have \(itemCount) items in your cart." 
     default : 
      return "You are an awesome customer!!" 
     } 
    } 
} 

Answer 1

你必須在case語句錯誤的地方冒號（:）。

func getCartStatus() -> (String) { 
    switch itemCount { 
    case 0 : 
    return "You have no items in your cart." 
    case 1...3 : 
    return "You have \(itemCount) items in your cart." 
    default : 
     return "You are an awesome customer!!" 
    } 
}