Question

这是我的代码。每次点击addButton时，我都会收到一个无法识别的选择器发送到实例崩溃/错误。我找了一个答案的过去一小时，却找不到答案。请帮忙。

@IBOutlet var addButton: UIButton!
@IBOutlet var resetButton: UIButton!

var number:Int = 0

override func viewDidLoad() {
    super.viewDidLoad()

    let size: CGSize = self.view.frame.size;

    countLabel.frame = CGRect(x: 0, y:0, width: size.width, height: size.height/4)
    minusButton.frame = CGRect(x:0, y: size.height/4, width: size.width/2, height: size.height/8);
    addButton.frame = CGRect(x:0, y:size.height/4 + size.height/8, width: size.width, height: 5*size.height/8)
    resetButton.frame = CGRect(x:size.width/2, y: size.height/4, width: size.width/2 ,height: size.height/8)

    addButton.addTarget(self, action: #selector(addNumber(sender:)), for: UIControlEvents.touchUpInside)
    minusButton.addTarget(self, action: #selector(minusNumber), for: UIControlEvents.touchUpInside)
    resetButton.addTarget(self, action: #selector(resetNumber), for: UIControlEvents.touchUpInside)

}

func addNumber(sender: UIButton!) {
    number = number + 1
    countLabel.text = String(number)
}

Answer 1

更改

addButton.addTarget(self, action: #selector(addNumber(sender:)), for: UIControlEvents.touchUpInside)

使用

addButton.addTarget(self, action: #selector(addNumber), for: UIControlEvents.touchUpInside)

Answer 2

您无需在选择器中包含发件人。因此，您需要将代码更改为

addButton.addTarget(self, action: #selector(addNumber), for: .touchUpInside)。

并且您不需要隐式解包发件人

func addNumber(sender: UIButton)

Answer 3

在选择器声明之前添加@objc关键字：

@objc func addNumber(sender: UIButton!) {
    number = number + 1
    countLabel.text = String(number)
}

添加目标时出现Swift错误

3 个答案: