单击按钮时会显示警报。我从列表中选择（如果有多少数据可用。）如何保存我从列表索引中选择的数据？

您可以在here上看到UI

我的帐户服务

class accountServices {
    static let databaseReference = Database.database().reference(withPath: "accounts").child((Auth.auth().currentUser?.uid)!)

    static var account = account()

    static func saveChanges() {
        databaseReference.setvalue(try! FirebaseEncoder().encode(accountServices.account))
    }

    static func getaccount() {
        databaseReference.observeSingleEvent(of: .value,andPreviousSiblingKeyWith: { (snapshot,_) in
            account = try! FirebaseDecoder().decode(account.self,from: snapshot.value!)
        })
    } 
}

变量

var product: ProductViewModel?

addButton点击

@IBaction func addToCartButtonTapped(_ sender: UIButton) {
    let alert = UIAlertController(title: "Bu ürünü hangi sepetinize eklemek istersiniz ?",message: "",preferredStyle: .actionSheet)
    var indexer = 0
    for cart in accountServices.account.cart! {
        if cart.product == nil{
            accountServices.account.cart![indexer].product = [Product]()
        }
        let action = UIAlertaction(title: cart.name,style: .default,handler: { (sender) in


            if let index = alert.actions.firstIndex(where: { $0 === sender }) {
                accountServices.account.cart?[index].product?.append(self.product) `//Error: Cannot convert value of type 'ProductViewModel?' to expected argument type 'Product'`
                    accountServices.saveChanges()//TODO...

                }
                let addAlert = UIAlertController(title: "Sepetinize Eklendi.",message: "Ürününüz sepetinize eklendi.",preferredStyle: .alert)
                let okButton = UIAlertaction(title: "Tamam",handler: nil)
                addAlert.addaction(okButton)
                self.present(addAlert,animated: true,completion: nil)
            })
            alert.addaction(action)
            indexer += 1
        }

        let cancelaction = UIAlertaction(title: "Vazgeç",style: .cancel,handler: nil)
        alert.addaction(cancelaction)
        present(alert,completion: nil)
    }
}