ios - 我试图让输入的数据进行计算并显示在标签中

Question

我正在尝试获取添加到主屏幕标签中显示的信息。我想让它计算利润，但我收到错误消息“‘String’类型的值没有成员‘text’”

@IBAction func addButtonTapped(_ sender: Any) {


    let alert = UIAlertController(title: "Product Information", message: nil, preferredStyle: .alert)
     alert.addTextField(configurationHandler: { (itemTextField) -> Void in
                itemTextField.placeholder = "Item"
     })
     alert.addTextField(configurationHandler: { (priceTextField) -> Void in
                priceTextField.placeholder = "Price"
     })
    alert.addTextField(configurationHandler: { (salePriceTextField) -> Void in
             salePriceTextField.placeholder = "Sale Price"
    })



     alert.addAction(UIAlertAction(title: "Add", style: .default) { (action) in
         let item = alert.textFields?[0].text ?? ""
         let price = alert.textFields?[1].text ?? ""
         let salesPrice = alert.textFields?[2].text ?? ""

        let itemPriceLabel = Double(price.text!)
        let salePriceLabel = Double(salesPrice.text!)

        if itemPriceLabel != nil && salePriceLabel != nil {

            let profitValue = Double (itemPriceLabel! - salePriceLabel!)
            ProfitLabel.text = profitValue
        }

         let product = Product(item: item, price: price, salesPrice: salesPrice)
        self.addProduct(product)


     })

     self.present(alert, animated: true, completion: nil)
     storeData()


}

Answer 1

您的 price 和 salesPrice 变量已经仅为字符串。但是您已尝试在下一条语句中访问 String 类中不存在的那些变量中的文本字段。

let itemPriceLabel = Double(price)
let salePriceLabel = Double(salesPrice)

并按如下方式分配您的值。

ProfitLabel.text = String(profitValue)