为addTarget - Swift 3向UIStepper函数添加选择器时出错

Question

我正在尝试将一个UIStepper合并到一个UITextField中，同时增加步骤器的值，UITextField用它将其更新为该值。我不断地发现错误：

‘NSInvalidArgumentException’，原因：‘-Calculator.plitViewController stepperValueChanged:：未识别的选择器发送到实例0x7fd730c0af30“

每当我运行我的应用程序，点击"+“按钮的步进。

有什么解决办法吗？我检查了我的选择器函数，我认为它看起来是正确的。

override func viewDidLoad() {
    super.viewDidLoad()

    partyOfStepper.autorepeat = true
    partyOfStepper.minimumValue = 1
    partyOfStepper.maximumValue = 99
    partyOfTextField.text = "\(Int(partyOfStepper.value))"
    partyOfStepper.addTarget(self, action: #selector(stepperValueChanged(stepper:)), for: .valueChanged)

}


@IBAction func calculateButtonTapped(_ sender: Any) {
}


func stepperValueChanged(stepper: UIStepper) {

    let stepperMapping: [UIStepper: UITextField] = [partyOfStepper: partyOfTextField]
    stepperMapping[stepper]!.text = "\(Int(stepper.value))"

}

Answer 1

正如Nariv所说，您的代码适用于我，请确保您以前没有在设计器中为UIStepper创建一个操作(签入连接检查器)：

import UIKit

class ViewController: UIViewController {

    @IBOutlet weak var partyOfStepper: UIStepper!
    @IBOutlet weak var partyOfTextField: UITextField!

    override func viewDidLoad() {
        super.viewDidLoad()

        partyOfStepper.autorepeat = true
        partyOfStepper.minimumValue = 1
        partyOfStepper.maximumValue = 99
        partyOfTextField.text = "\(Int(partyOfStepper.value))"
        partyOfStepper.addTarget(self, action: #selector(stepperValueChanged(stepper:)), for: .valueChanged)

    }

    override func didReceiveMemoryWarning() {
        super.didReceiveMemoryWarning()
    }

    func stepperValueChanged(stepper: UIStepper) {

        let stepperMapping: [UIStepper: UITextField] = [partyOfStepper: partyOfTextField]
        stepperMapping[stepper]!.text = "\(Int(stepper.value))"

    }

}