swift - 如何将 textField.text 值转换为整数并对两个整数求和

Question

Initialization of immutable value 'textfieldInt' was never used; consider replacing with assignment to '_' or removing it and textfield2Int

我收到两次关于 textfieldInt 的警告

这是我所有的代码:

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

您收到警告是因为，正如警告告诉您的那样，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，但您添加字符串 textField1.text! 和 textField2.text ! 在一起...

我想，您希望您的函数是这样的:

@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
}