執行應用程式內購買IOS，但是當我在按鈕輕敲我得到異常作爲fatel錯誤：數組索引超出範圍

Question

  MCIAPHelper.sharedInstance.buyProduct(self.fetchedProducts[0]) . // getting exception in this line 
     if let sender = sender as? UIButton { 
      sender.userInteractionEnabled = false 
      self.buttonToRestore = sender 
     } 
    } 

我創建按鈕購買，當我敲擊按鈕例外快到了，能有人建議我，我做錯了什麼。

Answer 1

確保您在fetchedProducts添加的項目也嘗試檢查之前使用它：

if fetchedProducts.count > 0 { 
    MCIAPHelper.sharedInstance.buyProduct(self.fetchedProducts[0]) 
    if let sender = sender as? UIButton { 
     sender.userInteractionEnabled = false 
     self.buttonToRestore = sender 
    } 
}