iOS无法识别的选择器发送到Swift中的实例 [英] iOS unrecognized selector sent to instance in Swift

问题描述

我在尝试让UIButton在用户按下时工作时遇到问题。我一直收到错误说：发送到实例的无法识别的选择器

I am having problems with trying to get a UIButton to work when the user presses it. I keep getting an error saying: unrecognised selector sent to instance

override func viewDidLoad() {
    super.viewDidLoad()

    button.addTarget(self, action: "buttonClick", forControlEvents: UIControlEvents.TouchUpInside)
    button.setTitle("Print", forState: UIControlState.Normal)
    button.font = UIFont(name: "Avenir Next", size: 14)
    button.backgroundColor = UIColor.lightGrayColor()
    self.view.addSubview(button)
}

func buttonClick(Sender: UIButton!)
{
    myLabelInfo.text = "Hello"
}

对于Swift方法，例如 func buttonClick（发件人：UIButton）传递给<$ c $的正确字符串是什么c> addTarget 选择器的方法？是buttonClick，buttonClick：，buttonClickSender：还是其他什么？

For a Swift method such as func buttonClick(Sender: UIButton) what is the correct string to pass to addTarget method for the selector? Is it "buttonClick", "buttonClick:", "buttonClickSender:" or something else?

推荐答案

您使用的是无效的动作的方法签名。你提供 buttonClick ，但该方法有一个参数，所以签名应该是 buttonClick：

You're using an invalid method signature for the action. You're supplying buttonClick, but the method has an argument, so the signature should be buttonClick:

button.addTarget(self, action: "buttonClick:", forControlEvents: UIControlEvents.TouchUpInside)

有关如何设置选择器格式的详细信息，请参阅下面链接的帖子中的接受答案。这篇文章中使用的代码可能是Objective-C，但它的所有课程也可以在这里应用。

For more information about how to format your selectors, you can refer to the accepted answer in the post linked below. The code used in this post may be Objective-C, but all its lessons can be applied here as well.

从带参数的方法名称创建选择器

并且作为旁注，如果您使用 Selector（buttonClicked：）作为操作，此代码也将有效，但您不必因为字符串文字可以隐式地转换为选择器类型。

And as a side note, this code would also be valid if you used Selector("buttonClicked:") as the action, but you don't have to because string literals can be implicitly cast to the Selector type.

引自将Swift与Cocoa和Objective-C一起使用

Objective-C选择器是一种引用
Objective-C方法名称的类型。在Swift中，Objective-C选择器由
Selector结构表示。您可以使用字符串
literal构造一个选择器，例如let mySelector：Selector =tappedButton：。因为
字符串文字可以自动转换为选择器，所以
可以将字符串文字传递给任何接受选择器的方法。

An Objective-C selector is a type that refers to the name of an Objective-C method. In Swift, Objective-C selectors are represented by the Selector structure. You can construct a selector with a string literal, such as let mySelector: Selector = "tappedButton:". Because string literals can be automatically converted to selectors, you can pass a string literal to any method that accepts a selector.

这篇关于iOS无法识别的选择器发送到Swift中的实例的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！