如何将textField.text值转换为Integer并将两个整数相加

Question

永远不会使用不可变值'textfieldInt'的初始化;考虑将赋值替换为'_'或删除它和textfield2Int

我为textfieldInt收到两次警告

这是我的所有代码：

class ViewController: UIViewController {

    @IBOutlet weak var textField1: UITextField!
    @IBOutlet weak var textField2: UITextField!
    @IBOutlet weak var output: UILabel!

    @IBAction func calculate(_ sender: AnyObject) {
        let textfieldInt: Int? = Int(textField1.text!)
        let textfield2Int: Int? = Int(textField2.text!)
        let convert = textField1.text! + textField2.text!
        let convertText = String(convert)
        output.text = convertText

}

Answer 1

您收到警告，因为，正如警告告诉您，您正在实例化textfieldInt和textfield2Int，但您没有使用创建的整数textfieldInt和textfield2Int计算为let convert，但您将字符串textField1.text!和textField2.text!一起添加...

我想，你希望你的功能是这样的：

@IBAction func calculate(_ sender: AnyObject) {
    let textfieldInt: Int? = Int(textField1.text!)
    let textfield2Int: Int? = Int(textField2.text!)
    let convert = textfieldInt + textfield2Int
    let convertText = String(convert)
    output.text = convertText
}